Previous studies have modified rice's resistant starch (RS) content by mutating single and double genes. These mutations include knocking out or reducing the expression of or genes, as well as overexpressing . However, the impact of triple mutant //OE- on RS contents remained unknown. Here, we constructed a double mutant with /RNAi-, based on with , and a triple mutant with /RNAi-/OE- , based on the double mutant. The results showed that the amylose and RS contents gradually increased with an increase in the number of mutated genes. The triple mutant exhibited the highest amylose and RS contents, with 41.92% and 4.63%, respectively, which were 2- and 5-fold higher than those of the wild type, which had 22.19% and 0.86%, respectively. All three mutants altered chain length and starch composition compared to the wild type. However, there was minimal difference observed among the mutants. The gene contributed to the improvement of 1000-grain weight and seed-setting rate, in addition to the highest amylose and RS contents. Thus, our study offers valuable insight for breeding rice cultivars with a higher RS content and yields.