Objective To study the possible mechanism of Yishen Shugan Fang（ YSSGF） in promoting the embryo implantation. Methods Female and male ICR mice（ in proportion of 3: 1） were fed in the same cage. At8: 00 of the next morning

vaginal plug of the female mice were checked

and the day was regarded as the first day of pregnancy when saw the plug. Then 50 mice with plug were randomly divided into normal control group

model group

progesterone group

and the TCM low and high dose groups

with ten in each group. Except the normal control group

the other four groups were given subcutaneous injection with mifepristone solution（ 0. 03 mg / kg） into neck and back to establish a model of obstacle of embryo implantation on the fourth day of pregnancy. Starting from the first day of pregnancy

the model group and the normal control group were given by gavage with 0. 2 ml of normal saline every day

the progesterone group was given subcutaneous injection with progestin solution 20 μl（ 2 mg / ml） every day

the TCM low and high dose groups were given by gavage with 3. 9g / ml and 15. 6 g / ml of YSSGF 0. 2 ml

respectively every day

all for seven days. On the eighth day of pregnancy

the mice were sacrificed

and the number of pregnant mice and total blastocyst with implantation were recorded to calculate implantation rate and average number of blastocyst with implantation. The uteri were also removed to detect the expression of MMP-2 and MMP-9 and protein content by the immunohistochemical method and the Western blot method. Results Compared with the normal control group

the number of pregnant mice

the implantation rate and the average number of blastocyst with implantation decreased significantly in the model group（ P < 0. 05）. Compared with the model group

the average number of blastocyst with implantation increased significantly in the TCM low and high dose groups and the progesterone group（ P <0. 05）

the expression of MMP-2 and protein content in uterus increased significantly in the TCM high dose group and the progesterone group（ P < 0. 05）

and the expression of MMP-9 and protein content in uterus were significantly higher in the TCM low and high dose groups and the progesterone group（ P < 0. 05）. Conclusion YSSGF may increase the average number of blastocyst with implantation of mice with obstacle of embryo implantation and improve the conception rate

and the underline mechanism may be related to increase the expression of MMP-2 and MMP-9 in uterus.