and calculate platelet sticking rate the result is shown in table 4 calculation method of platelet is as follows the result is shown in table 4 extract of cn03148281 3 can lower platelet number of normal rats markedly q 2 9260 p lt 0 05 comparing with normal saline group p lt 0 01 extract of present invention also can lower platelet number of normal rats markedly q 5 1399 p lt 0 01 comparing with normal saline group p lt 0 01 these two extract can both lower platelet number of normal rats but there is no distinguished difference between them q 2 2139 p gt 0 05 it is shown that extract of present invention and extract of cn03148281 3 can both lower platelet number and platelet sticking rate and decrease formation of thrombus extract of leech and earthworm called extract of cn03148281 3 is obtained with dry leech and dry earthworm referring to method in cn03148281 3 1 detection of visible extraneous material visible extraneous materials in extract of present invention embodiment 1 and extract of cn03148281 3 are detected respectively referring to chinese pharmacopeia 2005 edition praeparatum general notice injection rule the result is shown in table 5 the result shows that there is novel difference between extract of present invention and extract of cn03148281 3 in visible.