The invention belongs to the technical field of methyl alcohol synthesis, and specifically relates to a multi-section constant-temperature cold shock type methyl alcohol synthesizing reactor. The reactor comprises a tower body, wherein a plurality of rhombus distributors are arranged in the tower body; a temperature balancing device is arranged below each rhombus distributor; each temperature balancing device comprises a plurality of heat exchanging pipes which are horizontally arranged and parallel to each other, and a plurality of temperature sensors which are distributed at the upper and lower of the heat exchanging pipes; one end of each heat exchanging pipe is connected to a gas outlet pipe through a multi-way valve, and the other end is connected to a gas inlet pipe through another multi-way valve; an independent solenoid valve is arranged on each heat exchanging pipe; each gas inlet pipe extends to the outside of the tower body and is connected to an independent gas pump; a plurality of temperature control devices are arranged at the outside of the tower body. The reactor overcomes the shortages in the prior art and effectively reduces the problem that high bed layer temperature fluctuation leads to different activity of different-height catalysts; and the methyl alcohol synthesizing rate and the raw material utilization rate can be greatly increased.