The invention discloses a sodium bicarbonate filtrate thickening process and belongs to the field of chemical industry production. The sodium bicarbonate filtrate thickening process comprises steps asfollows: after a carbonized take-out liquid is separated by a hydrocyclone separator, crystal magma is delivered to a carbonizing take-out tank, a cyclone liquid is delivered to a sodium bicarbonatefiltrate thickener, and the carbonizing take-out tank takes out a finished product to a sodium bicarbonate filter machine; the sodium bicarbonate filter machine sprays washing water to reduce salinityof sodium bicarbonate, separated sodium bicarbonate is delivered to a calcination process, a filtrate of the sodium bicarbonate filter machine is pumped to a vacuum separator by a vacuum pump, separated filtrate flows into the sodium bicarbonate filtrate thickener through a U-shaped water seal, and the cyclone liquid flows into the sodium bicarbonate filtrate thickener after the carbonized take-out liquid passes the hydrocyclone separator; crystal magma is taken out from the lower part of the sodium bicarbonate filtrate thickener and conveyed to the carbonizing take-out tank through a crystalmagma pump, so that the crystal magma enters the sodium bicarbonate filter machine, a clear liquid overflows from the sodium bicarbonate filtrate thickener to a mother solution barrel I and then is pumped to an ammonia absorption procedure by a mother solution pump I. Energy consumption of production is reduced, the production problem caused by too high crystal-carrying amount is solved, and balance of system water of a combined-soda process is guaranteed.