The invention relates to the technical field of chemical engineering and particularly relates to a production method for preparing tripotassium phosphate and a byproduct special fertilizer for sunflowers. According to the fertilizer requirement of sunflowers, the effective absorptive amounts of nitrogen, phosphorus and potassium are analyzed and the element content in the production process is adjusted and matched, so that the prepared chemical compound fertilizer can satisfy the requirements of sunflowers to the maximum extent while the cost which is over-high caused by mismatch of elements in production of the compound fertilizer is lowered, thereby further preventing excessive elements from being put into soil to lead to solidification of the compound fertilizer so as to pollute the environment. The impurity removal cost when the conventional wet process phosphoric acid method is used for preparing a tripotassium phosphate product is lowered, so that the purity of the prepared tripotassium phosphate product is over 95%, the production cost is lowered by 93%, and the production method has a remarkable economic benefit.