Objective To investigate the gestational weight gain and quality of life in women with gestational diabetes mellitus(GDM) who used Free-Style Libre Flash Glucose Monitoring System. Methods From August of 2017 to January of 2019, the GDM patients diagnosed in the Department of Endocrinology in 3 ClassⅢ Grade A hospitals in Guangzhou were selected and divided into the observation group(n=39) and control group(n=43) according to their glucose monitoring willingness. The Free-Style Libre Flash Glucose Monitoring System was used for the observation group(sensor changed every 14 days) combined with the fingertip blood glucose monitor, it was necessary to monitor fingertip blood glucose contrast when hypoglycemia was identified by sensors. Pregnant women at other monitoring points could selectively monitor fasting and postprandial blood glucose. In the control group, after assigned into the group patients only monitored their fingertip blood glucose(at lease 2 times/d, including fasting and 2h postprandial blood glucose). The two groups were all instructed by self-management on diet, exercise etc according to the result of blood glucose monitor, the Wechat management was included to instruct them of the daily life diary recording method. World Health Organization-5 Well-Being Index (WHO-5) was adopted at the beginning of the study and the second week of follow-up to investigate the well-being index score of the patients in the two groups; at the end of pregnancy, the average perinatal blood sugar level, incidence of hypoglycemia events and the eligible rate of weight gain in different BMI patients were recorded. Results At the 2nd week, the score of well-being index in the observation group was higher than that in the control group with statistical significance(P=0.037).There was no statistically significant difference in fasting and 2 h postprandial glucose between the two groups (P＞0.05). There was no significant difference in blood sugar control (fasting and 2 hours after meal) between the two groups (P＞0.05), but the detection rate of hypoglycemia in the group using Free-style Libre glucose monitoring system was higher than that in the control group (P=0.042). By the end of pregnancy, stratified analysis showed that the qualified rate of weight gain in the observation group with BMI between 18.5 and 24.9 kg/m2 before pregnancy was higher than that in the control group with statistical significance(P=0.035). Conclusions The use of Free- Style Libre Flash Glucose Monitoring System in GDM patients makes gestational weight control more reasonable and painless, and improves the well-being index of patients.