"Most of the time" can be translated into Chinese as "大部分时间" or "绝大多数时间".

For example:

"I speak Engpsh most of the time." (我大部分时间说英语。/ 我绝大多数时间说英语。)
"He works on the computer most of the time." (他大部分时间在电脑上工作。/ 他绝大多数时间在电脑上工作。)