A glass lined reaction tank for chemical and pharmaceutical industries and a manufacturing method thereof. One-step molding technical standards for manufacturing iron blanks of the glass lined reaction tanks are deeply developed, an overall structure of a flanged big flange of a tank body and a tank cover matching with the tank body are innovated, and nominal pressure of the big flange and the sealing performance of a tank mouth are perfectly improved. By using a new structurally-combined precise controlled internal heating type electric furnace and an intelligent temperature program control/adjustment/recording instrument, heating temperature of an overall glass lining layer on an inner wall of the tank body is more accurately controlled to be the same, and a synchronous, integral and controlled sintering core technique is realized.