A control system for controlling a dry feed system to convey a solid fuel includes multiple sensors, a pressurizing gas controller, at least one assistant gas controller and multiple gas valves. The sensors generate multiple measurement signals signifying characteristics of the dry feed system. The pressuring gas controller calculates a feed tank pressure bias or/and a pressuring gas flow bias based on a solid flow rate and generates a first control signal based on the pressure bias or/and the pressurizing gas flow bias. The assistant gas controller calculates an assistant gas bias based on a solid loading ratio and generates a second control signal based on the assistant gas bias. The gas valves are driven by the first or/and second control signals to regulate the solid fuel. A control method is also described.