This study aimed to investigate and analyze the Problem-Based Learning and its influence on the ability of mathematical problem solving and mathematical disposition of students according to students' level of ability in grade XI Science program Senior High School (SMA) 4 Singkawang in the academic year 2013/2014. This is an experimental study in the form of one short case study and delayed test, and the research samples is 18 students were grade XI Science program Senior High School (SMA) 4 Singkawang. The research findings showed that the mean score in understanding problems was 11.44 of 14, the ability to plan the completion was 19.61 of 28, the ability to solv problems was 10.00 of 14, and the ability to recheck the results was 9, 06 of 14. There were differences in the ability of mathematical problem solving among students in the level of upper, middle, and lower after getting a math lesson using PBL approach. There were differences in the ability of students' mathematical problem solving in post-test and delayed test, a positive result of students' mathematical disposition, there was an interaction mathematical problem solving and the level of student ability