In this research, the effect of reducing procrastination tendency on the academic achievement of preservice science teachers in the physics course was investigated. In this, a quasi-experimental research design was used, which included the experimental and control groups. Each group consisted of 35 preservice science teachers. Both groups were taught a physics course at the undergraduate level by the same lecturer. While reducing procrastination tendency activities and strategies were applied in the experimental group, the conventional teaching method was applied in the control group. Data were collected by Physics Achievement Tests developed by the researcher for use in previous researches. Data analysis was tested, using IBM SPSS 22.0 statistical package program by taking into account the importance level between pre-test and post-test. After analyzing the data, in light of the findings of the research, the academic achievement of pre-service science teachers in the experimental group was found to be higher than the academic achievement of the candidates in the control group. Thus, it has been determined that special strategies and sanctions related to reducing procrastination tendency in the experimental group have a positive effect on achievement. For this reason, special strategies and positive sanctions can be applied to decrease procrastination tendency to increase the achievement in physics course of pre-service science teachers.