On the basis of theory of cryoscopy

the measuring process and the parameter selection of osmotic pressure molar ratio measuring system have been studied.A new method of negative temperature coefficient（NTC） thermistor linearization is brought up by using 100 μA constant current source power supply combined with 2 order norm least squares curve fitting algorithm

and also a Matlab correctional model of NTC thermistor is built up by which the NTC thermistor linearization problem is solved.On that basis

analog signal transform is carried out and with high resolution AD converter design of the osmotic pressure molar ratio measuring system is accomplished. According to the experimental verification

the osmometer is able to measure osmotic pressure molar ratio with a precision of ± 1 mmol / kg（≤500 mmol / kg） or RSD ≤ ± 0.2 %（> 500 mmol / kg）.