The invention discloses a water-based 
cutting fluid used in slice 
machining of a hard brittle 
crystal material, comprising the following compositions: 
base oil, organic amine, 
organic acid, synthetic ester, emulsifier, 
rust and 
corrosion inhibitor, dispersion 
flocculation and hard-water resisting agent, 
antiseptic bactericide, antifoaming agent, 
coupling agent, 
adjuvant and a proper amount of water. Aiming at the 
machining techniques of inner circle 
slicing and outer circle 
slicing, the water-based 
cutting fluid has good generality, 
lubricity, strong antirust property and a long service life; when the 
cutting fluid is used, the 
machining situation can be observed easily, the cooling property is good, the cleaning and the permeability are strong, cuttings subside easily, and the machining problems of machining error, crack and the like caused by cutter blocking, abrasion and the like are solved; according to the invention, the problems that cuttings are easy to adhere and suspend, a cutter is seriously abraded, a machined product cracks easily, the accuracy is not high, the machining efficiency is low, the later period cleaning is complex and the like existing in the current slice machining of the hard brittle 
crystal material are solved, and further, a 
machine bed is protected, and the cost is reduced.