NOVELTY - An olanzapine preparing method involves mixing 4-amino-2-methyl-10H-thieno(2,3-b)(1,5) benzodiazepine hydrochloride (II) and N-methyl piperazidine with diethylene glycol dimethyl ether to react, reducing pressure, distilling and recycling excess N-methyl piperazidine or reducing pressure, distilling and recycling the excess N-methyl piperazidine and diethylene glycol dimethyl ether solvent to obtain the crude solid olanzapine. The solid olanzapine is re-crystallized with ethanol solution. The re-crystallized mixture is filtered and dried to obtain the olanzapine product (I).    USE - Method for preparing olanzapine.    ADVANTAGE - The method enables eliminating need of solvent with large toxicity in preparation, reduces pollution, facilitates safe operation and fast reaction, reduces energy consumption, recycles excess raw material and solvent, decreases preparing cost, improves yield and ensures stable quality and high purity of the refined olanzapine by 99.5 percent.    DETAILED DESCRIPTION - An olanzapine preparing method involves mixing 4-amino-2-methyl-10H-thieno(2,3-b)(1,5) benzodiazepine hydrochloride and N-methyl piperazidine with diethylene glycol dimethyl ether to react, reducing pressure, distilling and recycling excess N-methyl piperazidine or reducing pressure, distilling and recycling the excess N-methyl piperazidine and diethylene glycol dimethyl ether solvent to obtain the crude solid olanzapine. The crude solid olanzapine is re-crystallized with ethanol solution. The re-crystallized mixture is filtered and dried to obtain the olanzapine, where molar ratio of the N-methyl piperazidine to 4-amino-2-methyl-10H-thieno(2,3-b)(1,5) benzodiazepine hydrochloride is 2: 1-20: 1, mass ratio of the diethylene glycol dimethyl ether to 4-amino-2-methyl-10H-thieno(2,3-b)(1,5) benzodiazepine hydrochloride is 2: 1-20: 1, mass ratio of ethanol to crude solid is 0.5: 1-10: 1 and ratio by volume of water to ethanol is 2: 1-20: 1. An INDEPENDENT CLAIM is also included for a method for refining olanzapine which involves reflowing the obtained olanzapine product to dissolve with the ethanol, decoloring by decoloring agent, filtering, cooling the filtrate at room temperature to separate crystals, filtering and drying to obtain the refined olanzapine, where a mass ratio of the ethanol to olanzapine is 5: 1-20: 1, and mass ratio of the decoloring agent to olanzapine is 0.1-10.0%: 1. The decoloring agent is diatomite or active carbon.