The 100A angle type fixed water level main valve consists of an angle type diaphragm main valve body, which is equipped with a special reinforced nylon diaphragm and a spring inside. The opening and closing of the main valve is controlled by a floating ball guide valve outside the main valve. When the water level in the pool reaches the set level, the float valve will close first and then the main valve will close accordingly. When the water level in the pool drops by about 10 centimeters, the float valve opens and the main valve opens to flush a large amount of water into the pool.