affter effect cant show the full video

You are trying to use After Effects as a video editing tool. It is not designed to edit video, it is designed to create shots that you cannot create in a nonlinear editor like Premiere Pro. The length of the preview depends on the available system resources. The source video in your project is an H.264 MPEG file. That means it is comprised of a few complete frames and a bunch of frames that are predicted by algorithms. That takes resources. Each pixel on each layer is loaded into memory so the things you want to do with those pixels can be calculated and a final pixel created and rendered to the screen. That is a completely different process than a media player or a video editing app uses. You will have to get used to working around those limitations and use AE for creating single shots and on occasion short sequences that you cannot create in your NLE. That what it was designed for. Some of my more complicated projects can take a couple of minutes a frame to render. Most of them take several seconds a frame to render at full resolution with all effects. 

To learn how to use After Effects properly spend some time with the User Guide provided by Adobe on the Product page, by a link in this forum, and even in the Learn workspace and Home Screen in After Effects.