Preparation method of bio-based polyether polyol

The invention belongs to the technical field of polyether polyol synthesis, and particularly relates to a preparation method of bio-based polyether polyol. Comprising the following steps: adding a certain proportion of lignin salt and a certain proportion of micromolecule amine into one or more bio-based initiators with different functionalities, and carrying out polymerization reaction with alkylene oxide under the action of a basic catalyst to obtain a bio-based polyether polyol product. According to the method, the renewable bio-based initiator is used for replacing a petroleum-based initiator to prepare the polyether polyol, the raw material source is wide, and the dependence on non-renewable resources can be reduced. By adding the lignin salt, the problems of low conversion rate and wide molecular weight distribution of biomass polyether can be solved, so that the alkane polymerization conversion rate of a general bio-based initiator with low purity is improved, the hydroxyl value of a polyether polyol p