We demonstrate a practical femtosecond laser absolute ranging system. High update rate and high precision arbitrary distance measurement can be realized based on nonlinear optical sampling between two free running polarization maintaining femtosecond fiber lasers. A ranging experiment for a cooperative target at about 2 m distance is demonstrated. A 3.3 μm ranging precision at 2 kHz update rate is realized. The ranging precision can reach 0.8 μm at 100 Hz update rate by averaging of continuous measurements. The ranging ambiguity is 2.08 m, which can be removed by introducing a coarse measurement with about 1 meter precision, resulting in an arbitrary ranging with micrometer precision. Due to the usage of all-polarization maintaining fiber based femtosecond laser sources, this ranging system is advantageous of high environmental stability, high compatibility, and maintenance free operation, which is attractive for a number of applications, such as large-scale manufacturing, aerospace engineering and remote sensing.