slow hybrid bike 700cx35c I'm using TRINX hybrid bike with stock 700cx35c tyres brand KENDA. Using Shimano SPD pedal with running shoe. stock groupset and wheelset. installed aero bars.

I always can't catch up in group riding. Even my friend with MTB with bigger tyre can ride with road bike. I've noticed I can't go more than 35km/h. Make me tired. Shift to higher gear or lower gear can't get my proper cadance.

Riding solo also feel like my bike very heavy to pedal. Only 18km/h. I can get 22km/h on aero bars. My average speed 23km/h. Being training 30km per ride flat road. No hill in my area so I cannot train for hills.

Got any advice to get faster? Change to hollow bottom bracket? Change tyre to 700cx25c? Thanks. And why MTB can go faster than me?
I second @SteveLoughran's advice to try skinnier tires (tyres), but maybe you also need more training.  Personally I'm either older, fatter, or both compared to the people in my weekly riding group, and I've always just been plain slow; I already have a road bike with skinny tires, so my only remedy is to put in the kilometers.  If I read your post correctly you're riding distances of 30 km, which isn't all that far.  If you do some longer training rides, of say 50 km, then 30 km will seem considerably easier.

Also consider interval training, which is a great way to get faster.  The basic idea is to go flat-out for short intervals during a normal training ride, with easy effort intervals in between to recover.  Perhaps three periods of maximum effort for three minutes each, with three-minute recovery intervals in between.  Articles about interval training abound on the web.  Intervals hurt, but they work.

Lastly, if you're lugging a few extra kilograms, it can't hurt to lose some.