A reagent splitting/dispensing method based on a reagent dispensing nozzle controls a split or dispensation amount of reagent, includes a waiting process of disposing a first air layer between an interface of the operation fluid and a nozzle tip end in the reagent dispensing nozzle; a first moving process of moving the reagent dispensing nozzle to a position above the reagent to be split; a second moving process of depositing the nozzle tip end in the reagent; an air layer adjusting process of increasing the occupation amount of the operation fluid in the reagent dispensing nozzle and decreasing the occupation amount of the first air layer, between the first moving process and the second moving process; and a reagent splitting process of decreasing the occupation amount of the operation fluid in the reagent dispensing nozzle and filling the reagent into the reagent dispensing nozzle from the nozzle tip end.