Abstract: Based on the practice of Matitan dam, the check calculation was carried out on stability and security in the metal structure under a condition of characteristic water level. The results showed that the strength and stiffness of sluice gate conformed to the standard, the gate safety monitoring should be strengthened in service. However, the strength of gate did not accord with the standard in the dam intake, while the stiffness met the need. In order to guarantee the safety operation of gate when the water level remained high status, a new gate with the high strength and high stiffness should be installed. Furthermore, the trash rack had a good working performance although the water level was high in the upstream of dam. The data may offer valuable information for the reinforcement of unsafe reservoirs. These findings can help us to evaluate the safety of the metal structure during the flood season.