The research aims to define the effectiveness of online learning on students' learning outcome in Craft Subject. Google Classroom was used as a Learning Management System (LMS) in the teaching-learning process. The subject of the research is junior high school students of grade 8 at SMP N 8 Semarang. The technique of data analysis was using simple linear regression to find out the relationship between one independent variable and have a straight-line relationship with the dependent variable. Data were obtained using a questionnaire and test. The results showed that the online learning can increase the effectiveness of students' learning outcomes. The increase in the quantity of students on the test results was suitable with the decision making that the significant value is 0.017 < 0.05 and the t count is 2.433 > t table 1.991. It can be concluded that the online learning using Google Classroom was effective to increase the students' learning outcomes in the Craft Subject at SMP N 8 Semarang.