Hi @yuhang
In order to connect your software with the Zapier Platform (and all 5000+ other apps supported by the Platform), that software will need to have a publicly-accessible API which you can use to build your Zapier Integration. You can find some high-level information about this concept at the link below:
https://platform.zapier.com/docs/zapier-intro
There is unfortunately no other way to connect without an API.
When you're ready to get started, the guide linked below offers a great introduction to building your first Zapier integration: https://platform.zapier.com/docs/start
Alternatively, depending on the functionality of your software and the automations that you'd like to create with Zapier, you might be able to achieve your goals using some of the strategies outlined here:
https://zapier.com/blog/add-any-app-to-zapier/
I hope this helps to get you pointed in the right direction!