The invention provides a precise chemical reagent compounding instrument which is applicable to chemicals, chemistries, medicines, foods, beverage, etc. which require solid-solid, solid-liquid and liquid-liquid precise compounding. The compounding instrument is characterized in that the precise chemical reagent compounding instrument comprises a liquid bell and hopper 4, a solid charging device 3 and a material selection device 2 which are arranged at the upper part of a position where a reagent bottle 5 is arranged, a temperature sensor 6 and a mixing device 8 which are arranged in the reagent bottle 5, a heating device 7 which is arranged at the bottom of the reagent bottle 5, a precision balance 9 which is arranged at the external part of the bottom of the reagent bottle 5, a PLC 10 which controls the material selection device 2, the solid charging device 3, the liquid bell and hopper 4, the temperature sensor 6, the heating device 7, the mixing device 8 and the precision balance 9. The compounding instrument of the invention has simple and convenient reagent compounding, realizes that the performance indexes such as temperature and density, etc. are fed back by query, automatic computation and data recording function, can be used in a laboratory for compounding a plurality of reagent and has the functions of recording, automatic conversion and output printing, etc., and has simple, convenient and scientific reagent compounding.