The invention provides an automatic gunpowder filling mechanism for firecrackers. A power cylinder installing plate, a positioning groove and a column in the automatic gunpowder filling mechanism are fixedly installed on a table face plate. A power cylinder is fixedly installed on the power cylinder installing plate, an inclined plane block is placed in the positioning groove, and the front end of the power cylinder is connected with the inclined plane block through an installing block. A lifting plate is slidably installed on the column through a sliding bearing, the upper end of a sliding part is fixed on the bottom surface of the lifting plate, and the lower end of the sliding part is contacted with the inclined plane block. A gunpowder box is fixedly installed on the side of the inclined plane block, and a gunpowder scraping block is installed on the lower end face of the gunpowder box. A measurement plate is arranged below the lifting plate and installed on the table face plate in an embedded mode. The gunpowder scraping block is contacted with the measurement plate. The automatic gunpowder filling mechanism for the firecrackers is simple in structure and convenient to use, firecracker gunpowder can be automatically measured and filled, production safety and production efficiency are improved.