The invention relates to the technical field of valve equipment, and discloses a feeding and discharging valve capable of achieving continuous sealing. The feeding and discharging valve comprises a communication pipe, a valve rod assembly, a force unloading assembly, a protection box, a control assembly, constant-pressure assemblies and a lead; the communication pipe comprises a shell; flanges arefixedly installed on the left side and the right side of the shell; a pipe cavity is arranged in the shell; the pipe cavity is divided into an upper empty cavity and a lower empty cavity, and a blocking piece is connected between the two empty cavities in a friction mode; a valve rod is fixedly installed at the top of the blocking piece; and a current-limiting rotating shaft movably sleeves the valve rod. The feeding and discharging valve is a constant-pressure electromagnetic valve for chemical industry; one constant-pressure assembly is arranged between two electromagnetic sheets, and the other constant-pressure assembly is arranged on the tops of the two electromagnetic sheets, so that a state that the air pressure is relatively balanced is formed between an isolation box and a cavityin a top plate; thus, the air pressure difference between the space between the two electromagnetic sheets and the outside is weakened, the problem of forced deformation of the electromagnetic sheetsis avoided, and the control accuracy of a numerical control computer is improved.