The cooler system of chiller water consists of two cycles which interconnected each other that is the primary cycle and the secondary cycle. This primary cycle is the cooler system of vapor compression and the secondary cycle is the water cooling system which is circulated and met the part of evaporator from primary system. This research is conducted to compare the value of COP (Coefficient Of Performance) by used two expansion devices that is thermostatic expansion valve (TXV) and capillary pipe which are attached in primary cycle for unit of water chiller. The result of test of performance indicates that cooler system of water chiller when operating with TXV has the value of COP equal 3.86 to 4.01, while with capillary pipe equal 3.59 to 3.74. The usage of TXV is capable to cool the evaporator output water (water chilled) to 10 o C, while at capillary pipe equal 12 o C. Thereby the application of TXV if it is used to the cooler system of water chiller having performance is better to be compared by using the capillary pipe.