Using Romaine lettuce(Lactuca sativa)as the test material，five different forms of magnesium fertilizers were selected and applied in the pot experiment，including magnesium sulfate(MgSO4)，magnesium chelate(Mg-EDTA)，magnesium oxide(MgO)，magnesium hydride(MgH2)，and magnesium(Mg)，with four magnesium concentrations of 0 mg/kg(L0)，3.5 mg/kg(L1)，7 mg/kg(L2)，and 14 mg/kg(L3)，to evaluate the effects of different forms of magnesium fertilizers on seed germination，yield and nutritional quality of lettuce，and clarify the types of magnesium fertilizers and application measures to enhance the yield and quality of lettuce.Compared to the control without magnesium fertilizer application，five forms of magnesium fertilizer at four application concentrations had different promoting effects on lettuce seed germination，plant height，aboveground fresh weight，and contents of chlorophyll，soluble sugar，soluble protein，and vitamin C.The addition of MgH2 at 3.5 mg/kg had the best effect on improving lettuce yield with the increase of seed germination rate by 65% and the increase of fresh weight of each plant by 102%，as well as improving its quality，the contents of chlorophyll，soluble protein，soluble sugar，and vitamin C was also significantly promoted.Adding Mg powder was the best way to improve the quality of lettuce，magnesium concentrations at L1 and L3 level significantly increased chlorophyll，protein content，soluble sugar content and vitamin C content ，reaching 70%，86%，373% and 120% ，respectively.The application of Mg-EDTA and MgO at 7 mg/kg magnesium not only increased lettuce yield but also effectively increased vitamin C content，reaching 412% and 374%，respectively.The application of MgSO4 at 3.5 mg/kg greatly enhanced soluble sugar content by 157%.The application of magnesium hydride，magnesium oxide，and magnesium powder increased the soil pH value.By conducting principal component analysis on various indicators to obtain comprehensive scores and ranking them，it was ultimately found that the growth physiology and nutritional quality indicators of lettuce were optimal when the magnesium concentration of magnesium hydride was applied at 3.5 mg/kg.