The invention discloses an improved manufacturing method of building composite plates. The method comprises the following steps of: 1,
grinding mulberry barks after dehydrating to obtain mulberry fibers, washing with water and filtering after carrying out
degreasing treatment on the mulberry fibers,
drying at the temperature of 80 DEG C, then dispersing ground
calcium carbonate and
gypsum into glue adhesives, mixing uniformly with the dried mulberry fibers, performing
hot pressing for 10 to 20 minutes at the temperature of 150 DEG C under the pressure of 10Mpa, and keeping the pressure until plates are cooled, manufacturing the plates of specified thicknesses and defining the plates as middle veneers; 2, respectively manufacturing poplars and Chinese firs to poplar veneers and Chinese fir veneers of the specified thicknesses, all using an outdoor
air drying method to control the
moisture contents of the poplar veneers and the Chinese fir veneers to be 20% to 50%; 3, applying the glue adhesives to the middle veneers by using an a glue dipping method, spraying carbon
powder to the middle veneers which are applied with the glue adhesives, and
drying for 1 hour at the temperature of 60 DEG C, and then applying the glue adhesives to the middle veneers by using the glue dipping method again. The improved manufacturing method disclosed by the invention reduces the manufacturing cost and enhances the production efficiency.