How to split mp4 and keep the original video format?

I cut the mp4 video into two parts, and render the first part I wanted, choose mp4 general quality, and foud the rendered part is larger than original video. it is weird, so I want to keep the original format, how to get the orignal parameter and set them in redering parameters?

First off, if your source videos use variable frame rates, their file size is inevitably smaller than what Kdenlive produces with a fixed frame rate (unless you chose a ridiculously low frame rate).

In order to get info about your source videos select the clip in the bin and open the Clip Properties tab.

If you are not adding anything (titles, effects, sounds, etc) and just want to cut a larger file into a smaller one without re-encoding, apps like LosslessCut and others can do the job. The cuts may not be accurate, though.