Abstract：In order to know the effect of cervical mucus on conception rate and offspring sex , 247 Simmental cervical mucus during the artificial insemination were collected in a breeding farm of Qilian County of Haibei, Qinghai Province, pH of the cervical mucus was measured. The results showed that the pH of cervical mucus was between 6.8 and 7.4, accounting for 83.8%,and average conception rate was 85.99%. The pH was lower than 6.6 for female Simmental, the average conception rate was 50%. While the pH was higher than 7.4, the average conception rate was 67.5%. The correlation data analysis showed that the higher pH of the cervical mucus, the more probability of male offspring. The less lower pH, the more probability of female offspring. The offspring were mostly female under pH ≤ 6.7. The offspring were mostly male under pH ≥ 7.4.