To investigate the clinical effects of different restoration methods on large area defect of deciduous molars.

A total of 150 deciduous molars were selected and randomly divided into three groups: A, B and C. Group A was repaired with glass ionomer and compound resin, B group was repaired by Hall technique, and C group was repaired with metal preformed crown. The successful rate of restoration in 6 and 12 months was compared between the three groups.

There was no significant difference between three groups in A, B and C (P > 0.05) in 6 months; the successful rate of 12 months repair in group B and C was significantly higher than that in group A (P < 0.05).

The success rate of Hall technique and metal performed crown is higher than that of glass ionomer and composite resin on the repair of large defects of deciduous molars.