[HELP] how to crop left and right black bars, keep ratio aspect at the same time?

[Selur]

1) how to crop and keep ratio aspect at the same time?

By default Hybrid will keep the par as it is.
So if the aspect ratio changed:
a. Hybrid didn't detect it properly then the Vapousynth/Avisynth Preview will be distorted too.
b. you messed with other settings

2) resolution will decrease when cut off all black bars, in this situation, i want to keep quality lossless at the same time, which encode mode to use is best?

That sentence does not make any sense.
if you want lossless: 1pass, constant quantizer, quantizer = , lossless

) mkv file is 1920×1080i 29.9fps, does it need to do deinterlace? to get a 1920×1080p 60fps file.

yes, to go from 1080i to 1080p you need either to deinterlace or apply IVTC, according to the flags the input is interlaced so you would need deinterlacing, if the flags are wrong the source could be anything, even progressive.

Cu Selur