An automated platelet function analyzer comprising: a sampling vessel, a preparation vessel, an analysis vessel, a sampling needle, a blood sample syringe, a platelet agonist syringe, an analysis solution syringe and a blood mixing device; the sampling vessel is used to store blood samples; the preparation vessel is used for the first blood sample dilution; the analysis vessel is used for the second blood sample dilution and the platelet number measure; the blood mixing devices are used for mixing the blood samples in the sampling vessel, the preparation vessel and the analysis vessel; the platelet agonist syringe is connected with the platelet agonist storage container so as to dispense platelet agonist into the sampling vessel; the analysis solution syringe is connected with the analysis solution storage container so as to dispense the analysis solution into the preparation vessel or the analysis vessel; the sampling needle, the blood sample syringe, the platelet agonist syringe and the analysis solution syringe are driven by motors separately; the sampling needle is connected to the blood sample syringe and the analysis solution syringe through pipes and valves respectively; as the blood sample syringe is connected to the sampling needle, in sequence transferring the blood samples to the sampling vessel, absorbing the partial blood sample from the sampling vessel and transferring it to the preparation vessel; absorbing the diluted blood sample from the preparation vessel and transferring it to the analysis vessel; and after the analysis solution syringe is connected to the sampling needle, the sampling needle will be cleaned. a sampling vessel, a preparation vessel, an analysis vessel, a sampling needle, a blood sample syringe, a platelet agonist syringe, an analysis solution syringe and a blood mixing device; the sampling vessel is used to store blood samples; the preparation vessel is used for the first blood sample dilution; the analysis vessel is used for the second blood sample dilution and the platelet number measure; the blood mixing devices are used for mixing the blood samples in the sampling vessel, the preparation vessel and the analysis vessel; the platelet agonist syringe is connected with the platelet agonist storage container so as to dispense platelet agonist into the sampling vessel; the analysis solution syringe is connected with the analysis solution storage container so as to dispense the analysis solution into the preparation vessel or the analysis vessel; the sampling needle, the blood sample syringe, the platelet agonist syringe and the analysis solution syringe are driven by motors separately; the sampling needle is connected to the blood sample syringe and the analysis solution syringe through pipes and valves respectively; as the blood sample syringe is connected to the sampling needle, in sequence transferring the blood samples to the sampling vessel, absorbing the partial blood sample from the sampling vessel and transferring it to the preparation vessel; absorbing the diluted blood sample from the preparation vessel and transferring it to the analysis vessel; and after the analysis solution syringe is connected to the sampling needle, the sampling needle will be cleaned.