In this paper, we fabricated PRT(platinum resistance thermometers) with the trimming technology using high fine laser system. U. V.(wavelength： 355nm) laser was mainly used for adjusting Pt thin films resistors to 100Ω at 0$^{circ}C$. Internationally, the accepted A-class tolerance of temperature sensor is ${pm}$0.06Ω at 0$^{circ}C$. according to DIN EN 60751. The width of trimmed lines was about 10$mu extrm{m}$ and the best trimming conditions of Pt thin films were power : 37mW, frequency : 200Hz and bite size：1.5$mu extrm{m}$. And 96 resistors, fabricated by photolithography and etching process, have 79∼90Ω and 91∼102Ω as the proportion of 45.7% and 57.3%, respectively. As result of sitting Pt thin films resistors to the target value(109.73Ω at 25$^{circ}C$), 82.3% of all resistors had the tolerance within ${pm}$0.03Ω and the others(17.7％) were within ${pm}$0.06Ω of A-class tolerance. The PRTs which wore fabricated in this research had excellent characteristics as follows； high accuracy, international standard TCR(temperature coefficient of resistance) value, long-term stability, wide temperature range, good linearity and repeatability, rapid response time, etc.