The aim of this study was to investigate the effects of the gender composition of university physics laboratory groups on student self-efficacy and quiz performance. Students from a Chinese university was chosen and subdivided into two groups, which were assigned either same-sex or coed laboratory teams while executing identical laboratory activities and instruction. Assessments were carried out prior to instruction and at the end of one semester. Students' self-efficacy and scores on laboratory quizzes were assessed. In this study, no statistically significant differences for the male students' self-efficacy gain and average laboratory quiz scores in the two types of team organization were found. In contrast, the female students' self-efficacy gain and lab quiz mean scores from same-sex teams were higher than ones from coed teams. So it delivered some messages to physics instructors and physics education researchers: Single-sex lab team education is beneficial for female students.