@echo off &setlocal enabledelayedexpansion
sort /rec 8192 1.csv /o 11.csv
(for /f "delims=" %%A in (11.csv) do for /f "tokens=1-2 delims=," %%a in ("%%~A") do (
	if "%%~a"=="!_a!" if %%b gtr !_b! set "v=%%A"
	if "%%~a" neq "!_a!" if defined v echo,!v!&set "_b=" &set "v="
	set "_a=%%a" &if not defined _b set "_b=%%b" &if not defined v set "v=%%A"
)
if defined v echo,!v!)>2.csv
::del /q 1.csv 11.csv
endlocal&pause&exit/b
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输出 1.csv 之前一定先按A列排完序的！
3楼代码已订正，先对 1.csv 排序再处理...
如须删除 1.csv, 11.csv 文件可剔除第9行开头的 :: 前缀即可...

Sub SortAndFilter()
' Order by Column A Asc,B Desc,and select B Max value rows into Sheet2.
On Error Resume Next
Dim rng As Range, oSort As Sort, sht1 As Worksheet, sht2 As Worksheet, i As Long, ii As Long
Dim col1, col2, aValue
col1 = 1 ' 第一列,有重复值
col2 = 2 ' 第二列,取最大值
Application.ScreenUpdating = False
With ThisWorkbook
    Set sht1 = .Worksheets(1)
    Set sht2 = .Worksheets.Add(After:=.Worksheets(.Worksheets.Count))
    Set rng = sht1.UsedRange
    Set oSort = sht1.Sort
    With oSort
        .SortFields.Clear
        .SortFields.Add rng.Columns(col1), xlSortOnValues, xlAscending
        .SortFields.Add rng.Columns(col2), xlSortOnValues, xlDescending
        .SetRange rng
        .Header = xlYes
        .MatchCase = False
        .SortMethod = xlPinYin
        .Apply
    End With
    rng.Rows(1).Copy sht2.Rows(1)
    ii = 2
    aValue = Null
    For i = 2 To rng.Rows.Count
        If IsNull(aValue) Or aValue <> rng.Cells(i, col1).Value Then
            'copy this row
            rng.Rows(i).Copy sht2.Cells(ii, 1)
            ii = ii + 1
            aValue = rng.Cells(i, col1).Value
        End If
    Next
End With
Application.ScreenUpdating = True
End Sub
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@echo off &setlocal enabledelayedexpansion
(for /f "delims=" %%A in (1.csv) do for /f "tokens=1-2* delims=," %%a in ("%%~A") do (
	if "%%~a"=="!_a!" if %%b gtr !_b! set "v=%%A"
	if "%%~a" neq "!_a!" if defined v echo,!v!&set "_b=" &set "v="
	set "_a=%%a" &if not defined _b set "_b=%%b" &if not defined v set "v=%%A"
)
if defined v echo,!v!)>2.csv
endlocal&pause&exit/b
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gawk -F"," "BEGIN{max[\"\"]=-999999}{if($2 ~ /^[0-9]+$/){if($2>max[$1]){max[$1]=$2;line[$1]=$0}}else{print}}END{for(key in line){print line[key]}}" 1.csv >2.csv
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再给楼主一个版本吧 请出 sort76.exe 和 jscript 保驾护航，可以轻松越过批处理读写每行8192字符量的大限... 以下代码存为 test.bat 运行，先从本坛第三方下载 sort.exe R7.6版 ( http://bcn.bathome.net/tool/7.6/sort.exe ) 更名为 sort76.exe 与 test.bat 同目录

@set @v=1 /* &echo off & sort76 -t "," -k1,1 -k2n,2 1.csv|cscript /nologo /e:jscript "%~f0">2.csv
pause&exit/b */
ws=WSH.stdin, _s='', _s1='';
while (!ws.atendofstream) {
	s=ws.readline(), ac=s.split(',');
	if (ac[0] != _s1 && _s1 != '') WSH.echo(_s);
	_s=s, _s1=ac[0];
}
WSH.echo(_s), WSH.quit();
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rem 另存为 ANSI 编码 bat
' & cls & %windir%\SysWOW64\cscript.exe /nologo /e:vbscript "%~f0" %* & pause & exit /b

f1 = "1.xlsx"    '源文件
f2 = "2.csv"     '输出文件

s = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & f1 & ";Extended Properties='Excel 12.0 Xml;HDR=YES'"
Set oConnection = CreateObject("ADODB.Connection")
oConnection.Open s
Set oRecordset = oConnection.OpenSchema(20)    'adSchemaTables
Do Until oRecordset.EOF = True
    Select Case oRecordset("TABLE_TYPE")
        Case "TABLE"
            s = oRecordset("TABLE_NAME")
    End Select
    oRecordset.MoveNext()
Loop
oRecordset.Close()
Set oRecordset = CreateObject("ADODB.Recordset")
oRecordset.CursorLocation = 3    'adUseClient
oRecordset.Open "SELECT 基因名称, MAX(基因长度) AS 基因长度 FROM [" & s & "] GROUP BY 基因名称", oConnection
s = ""
For i = 0 To oRecordset.Fields.Count - 1
    s = s & oRecordset(i).Name & ","
Next
s = Left(s, Len(s) - 1) & vbCrLf
Do Until oRecordset.EOF = True
    For i = 0 To oRecordset.Fields.Count - 1
        s = s & oRecordset(i).Value & ","
    Next
    s = Left(s, Len(s) - 1) & vbCrLf
    oRecordset.MoveNext()
Loop
oRecordset.Close()
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oTextStream = oFSO.OpenTextFile(f2, 2, True)
oTextStream.Write s
oTextStream.Close()
wsh.Echo "ok"
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