Preparation process of concrete water reducing agent

The invention relates to the field of concrete water reducing agents, in particular to a concrete water reducing agent preparation process which comprises the following steps: S1, heating a water reducing agent raw material naphthalene to melt; s2, adding molten raw material naphthalene into a reaction kettle filled with concentrated sulfuric acid, adding water after the reaction is completed, dropwise adding formaldehyde after the reaction is completed, dropwise adding liquid caustic soda after the reaction is completed again, and stopping after the pH value of the solution is adjusted to 7-9; s3, filtering, drying and crushing the solution obtained in the step S2 to obtain a basic water reducing agent; s4, the basic water reducing agent is guided into a grinding device to be ground, and the concrete water reducing agent is obtained; the grinding device comprises a grinding pipe used for being matched with the grinding roller for grinding, transmission rings fixed to the two ends of the grinding pipe and sid