The present study was conducted to analyze the pattern of plasma reproductive hormones including oestradiol-17β (E2),luteinising hormone (LH),follicle stimulating hormone (FSH),progesterone (P4) and testosterone (T) secretion and their interrelationships during the natural progenitive physiological stages (PPSs)viz.dioestrum,preoestrus,standing heat,days 5-10 post-copulation,days 60-90,120-150,180-210 and 240-270 of gestation,and days 2-30 postpartum in Dulong cattle (Bos frontalis),respectively.Blood samples of 46 Dulong cows were collected by jugular venipuncture in different PPS.The plasma E2,FSH,LH,P4,and T were analyzed by radioimmunoassay (RIA).During the PPS,two peaks of E2 profile were found on standing estrous(18.56±7.87 pg/ml) and on days 240-270 of pregnancy (11.85±3.45 pg/ml),lowest on 5- to 10- days post-copulation (P < 0.05).P4 concentration was found the highest on days 5-10 of post-copulation (9.35±2.84 ng/ml) (P < 0.01),the lowest on standing heat (0.29±0.13 ng/ml) which was significantly lower than that during gestation (P < 0.05).A biphasic FSH peaks were observed on the periods of estrous forepart (2.03±0.54 mIU/ml)and days 2-30 of postpartum (2.23±0.61 mIU/ml).Peak LH concentration was observed on days 5-10 of gestation (10.21±9.04 mlU/ml).Peak T level was found on days 240-270 of pregnancy,significantly higher than those in other PPS (P < 0.01).The significant positive correlations were found between the PPS and plasma FSH(r = 0.34,P < 0.05),P4(r = 0.31,P < 0.05),T (r = 0.48,P < 0.01) concentrations respectively,also found between plasma P4 and LH (r = 0.31,P < 0.05),and plasma T and FSH levels (r = 0.40,P < 0.01).It indicated that plasma testosterone plays an important role on regulation function of PPS in Dulong cows.However,a negative correlation was found between the concentrations of plasma E2 and P4 (r = -0.29,P < 0.05).The cows showed the sexual behaviors such as approaching bulls,raising tail,or mating when plasma E2 and FSH concentrations were high,plasma P4,LH and T concentrations were low.In different reproductive physiological stages,the hormone levels were relatively kept stabilization in LH and FSH during oestrum,pregnancy and parturition and so on,were adjusted by the change levels of E2,P4 and T.Especially,testosterone have an equal effect on normal estrous and holding together gestation in Dulong cow,which was the same function as E2 and P4.Dulong cows took on strongly reproductive capacity under a semi-management condition.