foreach my $key(keys %hash){
        if($key eq $name){
            if($hash{$key} == 10){
               ...

##</code><code>##

#!/usr/bin/perl

open (FILE1, ">10.txt") or die $!;
open (FILE2, ">20.txt") or die $!;
open (FILE3, ">30.txt") or die $!;

my %hash = (aw1 => 10, qs2 => 20, dd3 => 30,
            de4 => 10, hg5 => 30, dfd6 => 20,
            gf4 => 20, hgh5 => 30, hgy3 => 10);

{
     local $/ = "\n>";  # input record separator
     while (<DATA>){
          s/^>//mg;

          my ($name) = /^([^\n]+)/;
        
          if($hash{$name} == 10){
               select FILE1;
          }
          if($hash{$name} == 20){
               select FILE2;
          }
          if($hash{$name} == 30){
               select FILE3;
          }
          print ">$_";
     }
}

__DATA__
>aw1
ATGCTAGATGCTAGCTAGCTAGCACTGAT
CGATGCTAGCGTAGTCAGCTGATGCTGTA
CGATGCTAGTCGTACG
>qs2
CGAGCTAGTCGTAGTCGTGATGCTGATTA
CGATGCTAGTCGTAGCTAGCTGATGCTGC
CGATGCTAGTCGTAGTC
>dd3
CGTAGTCGTAGTCGTAGTCGATGCTGATG
GCTAGTCGATGCTAGCTAGTCGATGCTGG
CGATGCTGAT
>de4
CGTAGTCGTAGTCGTACGTAGTCGTGAGT
CGATTATTTAGGAGGGACAAGGATAGTA
>hg5
CGTAGTCGTAGTCTAGTCGTGATGCTAGA
>dfd6
CGATGCTACGTACGTAGTCAGTCGTGATG
AATTAGAGCAGATAGAGGGGGAAAGGGTT
AAACCCC
>gf4
CGTAGTCAGTCTAGCTGATGTCGATGCTG
>hgh5
CATGCTAGTCGTAGTCGTAGTCGATGCTT
TTTTAAGGGAACCCCC
>hgy3
CCCCGGGTTTGGGAAAAGGGGGGGGATAG