If you are applying Canadian universities, I can give you some advice.

Generally, Canadian universities accept the grading system in China.

That means, you don't need to convert your grades.

The requirement in good univerisities is 85/10, while some universities only require 80/100.

If you do want to convert your grades, or the university you applied has such a requirement, then you should use the following table:

90or above --> A+ 4.3
85-89 --> A 4.0
80-84 --> A- 3.7
75-79 --> B+ 3.3
70-74 --> B 3.0
65-69 --> B- 2.7
60-64 --> C+ 2.3

Most of the universities in Canada use the above table, but some universities do have their own grading system. Some have a 4.0 base grading system.

And some others rate 85 or above as A+. And sometimes the grading system is different from department to department.

You should convert every course to 4.3 based grade and then calculate the average. At last you write the GPA as *.*/4.3 Some Chinese universities write their converting table in the transcripts.

In that case, I think you will have to follow your university.