VB.net中如何求出2维数组，每个维度上的值得个数

每行的数字个数不同,你说的这是不规则数组,解决方案如下:
Dim b As String = ""
Dim a As Integer()() = New Integer(9)() {}
a(0) = New Integer() {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
a(1) = New Integer() {0, 3, 4, 5}
a(2) = New Integer() {0, 4, 5, 6, 7}
a(3) = New Integer() {0, 6, 5, 8, 9, 1}
a(4) = New Integer() {0, 2, 5, 1, 7}
a(5) = New Integer() {0, 4, 2, 6, 7, 3}
a(6) = New Integer() {0, 4, 5, 3, 2}
a(7) = New Integer() {0, 4, 1, 6, 2, 8, 5, 3}
a(8) = New Integer() {0, 4, 9, 6, 3, 5, 7}
a(9) = New Integer() {0, 1, 5, 9, 7, 6, 2, 4, 3, 8}
For i As Integer = 0 To a.GetUpperBound(0)
b &= "第" & i + 1 & "行有" & a(i).GetUpperBound(0) + 1 & "个数" & vbCrLf
Next
MessageBox.Show(b)

不知道你所说的循环检测是什么意思，不过VB.net测定数组维度可以用Ubound()
for i=0 to Ubound(a)
print "第" & i & "维：" & Ubound(a(i)) & "个元素"
next i