Provided is an underseal opening type full-bore cementing sliding sleeve. The underseal opening type full-bore cementing sliding sleeve comprises an upper joint, a lower joint, a central pipe, a rupture cylinder, a sliding sleeve, an inner cylinder, and an outer cylinder, the upper end and the lower end of the central pipe are respectively connected with the upper joint and the outer cylinder, the bottom end of the outer cylinder is connected with the lower joint, the central pipe is connected with the sliding sleeve via a shear pin, the upper end of the inner cylinder is connected with the sliding sleeve, the lower end of the inner cylinder is tangent to the lower joint and can slide along the lower joint, a sidewall of the central pipe is provided with a fracturing hole, the outside of the central pipe is provided with the rupture cylinder capable of sealing the fracturing hole, a containing cavity used for fixing a snap ring is formed between an inner side surface of the outer cylinder and the central pipe, the snap ring is embedded into the containing cavity, the outside of the inner cylinder is provided with a groove matched with the snap ring, and the distance from the groove to the snap ring is greater than the distance from the top end of the sliding sleeve to the lower edge of the fracturing hole. According to the underseal opening type full-bore cementing sliding sleeve, the sliding sleeve can be opened via lower falling of a packer string in a shaft, the sliding sleeve is communicated with an oil gas layer, the operation is convenient and reliable, full bore in the shaft is realized, and convenient conditions are provided for the subsequent construction operation.