is high school graduate only qualify in CEC?
We do not know the specifics of your situation, but CEC does NOT require a certain level of education. However, it does require 2 years of Canadian work experience in a SKILLED occupation (NOC Level O, A or B).
There are a number of occupations classified as "skilled" that do not require college/university diplomas.
So, the short answer - yes, it is POSSIBLE for someone with a high school education to qualify for CEC.