My fan on my Mac has been running all the time. I did google some solution for this problem. However, I didn't see any error on the system.log Could anybody have any better recommendation for my Mac.
My best guess would be that launchd is trying to launch something that is failing and it's just trying over and over and over again. I remember seeing something similar before.
First thing I'd recommend is downloading and running EtreCheck. Amongst other things this will look at all your launch agents and launch daemons scripts and point out any that have missing components that might result in this repeated behaviour.
Look for items highlighted in red like in the screenshot below.