Objective To investigate the characteristics of diet in patients with gestational diabetes mellitus(GDM) and analyze their dietary nutrition.Methods Clinical data of 978 cases of pregnant women in our hospital were collected and divided into GDM group(458 cases) and the healthy control group (520 cases).Dietary questionnaire was designed and diet characteristics were analyzed retrospectively.Daily calories and nutrients intake were calculated by software calculation.Results There were significant differences on the dietary pattern between the two groups:daily coarse grains:(35.12 ±4.87) g vs (46.35 ±5.23) g;seafood:(22.10 ± 8.45) g vs (39.34 ± 12.45) g;grilled:(6.72 ± 1.76) g vs (3.45 ±0.34) g;fried:(25.34 ± 7.84)g vs (10.56 ±4.76) g;sausage:(5.38 ± 1.81) g vs (3.45 ± 0.45) g;dessert type products intake:(50.41 ±20.76) g vs (35.86 ± 10.45) g (t =2.582,10.346,15.452,20.239,18.195,8.472,respectively,P ＜0.05).There was only significant difference between the two groups on calcium supplements in daily intake of nutritional supplements(GDM group 43.89％,control group 72.69％,x2 =83.660,P ＜ 0.001),and there was no significant difference on the rests(all P ＞ 0.05).Vitamin A,B1,B2,C and calcium,iron,zinc,selenium daily intake in GDM patients were less than those in the control group,but there was significant difference only in calcium compared with the control group (GDM group (785.2 ± 194.5) mg,control group (945.5 ± 245.2)mg,t =2.795,P =0.005).Multivariate logistic regression found that excessive intake of fried class (OR =3.357,95％ CI =2.012-11.340),barbecue (OR =2.652,95％ CI =1.834-8.578),sausage type products (OR =2.518,95％ CI =1.743-7.421) etc.were dietary factors of GDM (all P ＜ 0.05).Incidence of GDM was significantly increased if taking more.While the increased intake of coarse grains (OR =0.632 95％ CI =0.134-1.489),seafood class(OR =0.408,95％ CI =0.105-1.189) can reduce the occurrence of GDM(all P ＜ 0.05).Conclusion Many unscientific ways of eating involved in pregnant women with GDM.Dessert,sausage,grilled,fried products intake increased the risk factors for GDM.Coarse grains,seafood intake were the protective factors of GDM.Timely adjustment of maternal diet and adequate calcium supplementation played an important role in the prevention of GDM.