The invention belongs to the field of 3D printing resin, and particularly relates to alkaline phenolic resin for 3D printing of a low-free liquid formaldehyde process and preparation and application of the alkaline phenolic resin. The invention provides low-free liquid formaldehyde alkaline phenolic resin, which is prepared from the following raw materials in percentage by weight: 30 to 50 percent of main phenols, 5 to 20 percent of liquid formaldehyde, 5 to 20 percent of pH value regulator, 5 to 20 percent of secondary phenols, 5 to 20 percent of alcohol solvent, 5 to 20 percent of stabilizer, 5 to 20 percent of coupling agent, 5 to 20 percent of modifier and 5 to 20 percent of liquid formaldehyde reducing agent. 0.1%-1% of a pH regulator, 5%-15% of secondary phenols, 20%-40% of an alcohol solvent, 1%-5% of a stabilizer, 0.1%-0.5% of a coupling agent, 0.01%-0.5% of a modifier and 0.1%-0.5% of a liquid formaldehyde reducing agent. A 3D printing product printed after the product is used can achieve high tensile strength and high temperature resistance, and the resin has the advantages of being environmentally friendly, easy to degrade, high in bonding strength, stable in storage, long in storage time, simple in preparation process, low in cost and the like, and does not affect the dimensional precision of a printed part.