It seems when I'm reducing the gears, the whole car kinds of having knocking. So I jacked and inspected the mounts. Please see the pictures, are those seems good for your eyes?
Need replacement?

 

tough to tell from the pic. I'd go the next level and test for any engine movement with power on/off (ie power brake) or jack the engine to see if the mount center moves. Do you see any tears in the rubber?

 

seems to me something looks wrong about the first one. the bushing doesn't seem to fill the entire ring, and the bolt is well below the center. I will claim absolutely zero expertise on engine mounts, but that just doesn't look right to me.

 

When my motor mounts were bad I noticed the whole car would shake when in gear and my foot on the brake pedal.