The invention discloses a production method of water coal slurry. The method comprises the following steps: mixing VAE wastewater with coal ash and grinding, wherein the VAE wastewater contains VAE and water; adjusting the pH value of the VAE wastewater to be 7-9. According to the production method, the VAE wastewater is adopted for replacing clear water to prepare the water coal slurry, so that the treatment expense of chemical wastewater is reduced, the subsequent treatment problem of the wastewater is solved, and the combustion performance requirement of the prepared water coal slurry can be met.