Abstract: CaCO3 and CaSO4 were used as the extender pigment mixed into the polyurethane varnish and polyurethane varnish. The three kinds of materials dubbed in different finishing processes, and the obtained paints were used for surface decoration of birch. The paper separately tested the basic material finishing process to the surface glossiness, film adhesion, the film wear resistance and fire retardant properties. The change of film properties was discussed. The results showed that the coatings containing CaCO3 extender pigment had the best wear resistance. The amount of extender pigment had a certain influence on the adhesion of film. When the mass ratio of extender pigment to PU was less than 150∶66, the adding amount of extender pigment had no effect on the adhesion of the film. When the mass ratio of extender pigment to PU exceeded 200∶66, the increase of the extender pigment would reduce the adhesion of coating. The arrival time of second peak in the heat release rate curves of CaSO4 extender pigment was delayed 45 s less than birch. At the same time, the effective heat of combustion decreased, specific extinction area increased, the residual mass ratio was the highest. All these indicated that this extender pigment had a certain degree of flame retardancy.