Objective To investigate the impact of improved stoves on skeletal fluorosis in Bijie city,a coal-burning type endemic fluorosis area in Guizhou province.Methods In accordance with the severity of skeletal fluorosis and the time length of using improved stoves,four villages of Bijie city in Guizhou province were sampled as the survey sites,they were Shadi village(a disease lightly affected area with short-time usage of improved stoves) of Haizijie town,Xiaba village(a disease lightly affected area with long-time usage of improved stoves) of Yachi town,Zhongtun village(a disease seriously affected area with short-time usage of improved stoves) of Ganxi town and Maoliping village(a disease seriously affected area with long-time usage of improved stoves) of Bazhai town.Villagers aged 12 and above were randomly sampled as research subjects in the four villagers.All research subjects were taken X-ray of pelvis,anteroposterior X-ray of right forearm and right leg using DR imaging systems,and diagnosed according to the diagnostic criteria of "Diagnostic Criteria for Endemic Skeletal Fluorosis" (WS 192-2008).Results ①Two hundred eighty people were examined in the four villages,X-ray detection rate of skeletal fluorosis was 28.21％ (79/280),no severe patients were detected,the detection rates of patients in moderate or mild stage were 5.36％ (15/280) and 22.86％ (64/280),respectively.②The detection rates of lightly or seriously affected areas of coal-burning type fluorosis were 26.92％ (35/130) and 29.33％ (44/150),respectively,and the difference was not statistically significant between the two groups(x2 =0.200,P ＞ 0.05).The detection rate of moderate skeletal fluorosis[9.23％(12/130)] in the disease lightly affected area was higher than that of the disease seriously affected area[2.00％(3/150),x2=7.182,P ＜ 0.05],and no significant difference statistically of the rates of mild disease was found between the two groups[17.69％(23/130) and 27.33％(41/150),χ2 =3.671,P ＞ 0.05].③The detection rates of the disease in long or short time usage of improved stoves' groups were 20.41％(20/98)and 32.41％(59/182),respectively.The difference was statistically significant between the two groups(x2 =4.536,P ＜ 0.05).Conclusions The disease situation of coal-burning fluorosis is under control in Bijie city after using improved cooking stoves,but prevention measure is still very important.