This research aimed to know the effectiveness of CTL Science Worksheet to improve the process skill for 4^th grade of primary students. This research used quasi experimental design in nonequivalent pre-post control group design. Based on the results of the effectiveness test, the gain score (N-gain) of experimental group showed (0.70) > control group (0.35) and student process skill have improved for each indicator. Based on the research that have been done, it concluded that CTL Worksheet capable to improve the process skill of 4^th grade student.