Objective  To explore the relationship of accommodative convergence/accommodation （AC/A） and accommodative lag， and learn the possible role of heterophoria in the development of the myopia. Methods  It was a cross-sectional study. We selected the juvenile myopes with heterophoria 62 persons（124 eyes） in all， tested their diopter， the degree of horizontal phoria， AC/A and accommodative lag. According to the low， medium and high myopia， we divided them into three groups， and compared the AC/A， accommodative lag of esophoria with exophoria in these three groups and in the meantime， the heterophoria with AC/A and accommodative lag is analyzed. Results  In low myopia group， AC/A and accommodative lag in esophoria is （4.72±0.38）△/D， （0.50±0.20）D respectively， and in exophoria， is （3.45±0.31）△/D， （0.20±0.10）D respectively. In moderate myopia， AC/A and accommodative lag in esophoria is （5.33±0.42）△/D， （0.58±0.08）D respectively， and in exophoria， is （3.26±0.25）△/D， （0.30±0.13）D respectively. In high myopia， AC/A and accommodative lag in esophoria is （4.01±0.38）△/D， （0.50±0.12）D respectively， and in exophoria， is （2.50±0.29）△/D， （0.28±0.12）D respectively； both between AC/A and accommodation lag are statistically significant difference （P<0.05）. The esophoria  degree correlation positively with AC/A （r=0.670， P<0.05） and accommodation lag （r=0.430， P<0.05）. The exophoria degree correlation negatively with AC/A （r=-0.331， P<0.05）， and correlation positively with accommodation lag （r=0.423， P<0.05）. Conclusion  In myopia  patients， AC/A and accommodation lag in esophoria are greater than exophoria， and the esophoria  degree correlation positively both with AC/A and accommodation lag， so we speculate that the patients with esophoria their degree of myopia development more quickly than exophoria， the greater the degree of esophoria， the quicker the degree of myopia developments. The exophoria degree correlation negatively with AC/A， and correlation positively with accommodation lag， so we surmise that the large degree of exophoria plays an important role in the development of myopia through the bigger accommodative lag.