Hi,
I can see you have 2 Src NAT rules. Which one are you deactivating when you say "when I enable source nat in srx , a client computer behind paloalto can't communicate with client behind srx"?
Can you run flow traceoptions when the traffic is not working properly:
# set security flow traceoptions file TRACE # set security flow traceoptions flag basic-datapath # set security flow traceoptions packet-filter TEST source-prefix 172.16.0.0/16 # commit [try sending traffic from 172.16.0.0/16] # run show log TRACE