p-Hydroxybenzaldehyde is an important intermediate of pharmaceutical, perfume, liquid crystal. It can generate anisaldehyde when having reaction with dimethyl sulfate, and can generate hydroxy cinnamic aldehyde upon its reaction with acetaldehyde which can further undergo oxidation to obtain cinnamic acid. The direct oxidation of this product can prepare hydroxybenzoic acid; Its reduction can generate p-hydroxyphenyl rmethanol; both of them can be used as spices; pharmaceutical intermediates; raw material of liquid crystal; other kinds of organic synthesis intermediates with a wide range of applications.