vnoremap <M-=> :call Duiqi('\v(^\s*\S+)\s+(.*)')<CR>  

"reg匹配的第2段文字对齐

function! Duiqi(reg)

    let l0 = line("'<")

    let l1 = line("'>")

    "获取第1个单词及前面空格的最大长度

    let max = 0

    let arr = {}

    let l = l0

    while l <= l1

        let arr[l] = matchlist(getline(l), a:reg) "把字符串分成2段

        let len = strlen(arr[l][1])

        let max = (len > max ? len : max)

        let l += 1

    endwhile

    let max += 1 "最长的后面要放一个空格

    "设置strSpace

    let strSpace = CreateSpaces(max)

    "开始对齐

    let l = l0

    while l <= l1

        call setline(l, arr[l][1].strpart(strSpace, 0, max-strlen(arr[l][1])). arr[l][2])

        let l += 1

    endwhile

endfunction  

"生成n个空格的字符串

function! CreateSpaces(n)

    let s = ''

    for i in range(a:n)

        let s .= ' '

    endfor

    return s

endfunction

'\v^\s*(\S+)\s+(.*)'