The pre-experimental approach was used in this study. The students in XI IPA1, out of a total of 28, were chosen as the sample by the researcher using a random sampling procedure. Speaking tests in the form of oral exams served as the research tool. After then, descriptive and inferential statistics were used to examine the collected data. The data analysis's outcome demonstrated that the level of significance (0.05) was greater than the probability value (0.00). This demonstrated that the use of Plan-ahead Brainstorming improved the students' ability to communicate. This suggests the acceptance of the alternative hypothesis (H1). This study made a significant contribution to the theory of the use of plan-ahead brainstorming to improve students' speaking abilities. The method that can most effectively affect students' speaking fluency is plan-ahead brainstorming. The outcome of the use of plan-ahead brainstorming is useful in learning English, especially students in learning speaking. The student can decrease their anxiety and stammer in plan-ahead session to prepare what they want to utter. The researcher found that this technique is useful for teachers in order that they can use this technique more effectively as long as the teacher prepare specific time to implement this technique in several time.