This research aimed to find out the effectiveness of Code Mixing as a teacning and learning method on students’ English speaking. It also wanted to discover a significant difference by comparing samples who got the treatment by using code mixing and who were not in the 12th grade students MA An-Najah Payabenua. The method used in this study was quantitative and the design used in this study was quasy-experimental design. The total of population were 36 students that included from two classes, with 18 placed as experimental group and 18 as control group. The focused in this study were restricted: vocabulary, pronunciation, comprehension, and fluency. Pre-test and post-test procedures were used by researcher to assess pupils’ speaking skill. The test was analyzed by SPSS 26. The observation outcome declared, code mixing as teaching and learning method in-creased students’ participation, motived and increases students’ confident in their oral skill. The research found that the mean in experimental class (Mean=71, 5625) was higher compared to control class (Mean= 57, 38194444). In conclusion a significant effect on students’ speaking skill by using code mixing was discov-ered.