The critical points and continuous cooling transformation curves of steel 14CrlMoR (/% ：0. 01C

0. 66Si

0. 80Mn

0. 006P

0. 003S

1.72Cr

0.31 Mo

0. 01 Nb) are measured by dilatometer

and the effect of cooling rate on structure and microhardness of test steel is studied. Results show that with cooling rate 0. 1 ~ 1℃ /s the transformed structure of tested steel is ferrite and pearlite； with 2 ~5℃ /s the tested steel obtains mixed structure of ferrite

pearlite and minor granular bainite； with 10℃/s the structure of test steel is ferrite and granular bainite； with 15 ~20℃/s the structure is lath bainite ；and with 25 ~5℃/s the steel gets the mixed structure of lath bainite and martensite.