Self-regulated learning (SRL), as one of the most crucial factors of students' academic performance, has received much concern in blended learning (BL), especially for pre-service teachers. Therefore, finding effective ways to improve pre-service teachers' SRL is of great importance. Ninety-five pre-service teachers participated in this study. We developed a learning diary and a training plus pre-warning system (TPS) based on a process model of SRL in BL. The objective was to investigate the effects of the learning diary and the TPS on fostering pre-service teachers’ SRL skills in BL. The effects were evaluated by means of analysis of variance and time-series analyses. Results showed that the TPS improves more sub-skills of SRL than the learning diary. The present study suggests that the TPS generates an effective way to help pre-service teachers become self-regulated learners. • The different effects of the interventions were analyzed using multi-group ITSA. • The learning diary is an appropriate instrument recording the learning process. • The training plus pre-warning system is helpful for self-regulated learners.