The invention relates to the field of production of 
viscose fibre in the 
textile industry, in particular to a method for preparing 
sodium sulfide from 
hydrogen sulfide waste gas produced in the production of the 
viscose fibre. The method comprises the steps as follows: A, the 
waste gas is fed into an alkali 
spray tower; B, 
hydrogen sulfide is absorbed in an alkali liquor in the alkali 
spray tower; C, impurities are removed; D, a preheated absorption liquid is delivered into a primary multi-effect 
evaporator; E, a solution is subject to settlement and 
desalination; F, the desalinated solution is filled into a semi-finished product 
barrel, and caustic soda is added into the desalinated solution; G, the solution in the semi-finished product 
barrel is delivered into a secondary single-effect 
evaporator; H, after undergoing the secondary 
evaporation, the solution is filled into a finished product 
barrel, and then is stirred for 
crystallization; and I, 
crystal sodium sulfide is made into tablets. The method has the 
advantage of realizing the optimal generation of 
sodium sulfide through the setting of 
processing parameters such as the size of main equipment, the 
pore diameter of a delivery pipeline, wind volume, wind velocity, the concentration of the alkali liquor, 
absorption time, circulating 
evaporation time, 
evaporation temperature, evaporation vacuum degree, 
precipitation time, stirring velocity, the rotational speed of a tablet making 
machine, and the like.