18個月內上過不能再上

http://www.courts.ca.gov/9410.htm

You CANNOT go to traffic school for:

Equipment offenses
Non-moving offenses (like parking offenses)
Misdemeanors
Offenses with a mandatory court appearance
Alcohol-related offenses
Offenses in a commercial vehicle

You are also NOT eligible for traffic school if you have gone to traffic
school for another ticket that you got in the last 18 months.

There are other reasons you may not be eligible for traffic school. For more
information on eligibility for traffic school, see the California Rules of
Court, rule 4.104.

Talk to a lawyer if the court says you are not eligible for traffic school
but you believe you should be.