A control method for preheating and roasting processes during the production of a traveling grate machine belongs to the technical field of the control of the pellet production through the traveling grate machine. The invention aims to provide a judgment and control method for preheating and roasting processes during the pellet production process via the traveling grate machine. The method comprises the following steps: carrying out regression fitting of the exhaust temperatures all bellows in a burner section and two bellows behind the burner by utilizing a least squares method so as to obtain a 6-time temperature curve, wherein the X-axis represents the positions of the detection points, and the Y-axis indicates the temperatures of the detection points; carrying out derivation for a curvilinear equation so as to obtain a slope equation, wherein the X-axis value of the maximal slope point is the preheating termination point which is the reference for the quantitative partition of the preheating and the roasting; and based on the obtained preheating termination point, automatically adjusting the rotational speed of a main induced-draft fan according to the set value of the preheating termination point so as to realize the automatic control of the preheating termination point. According to the invention, the pellet production through the traveling grate machine is stable and the pellet quality is improved.