At present,the application of Photonic Doppler Velocimetry is mostly aimed at measuring instantaneous and short term impact,vibration or the velocity of flying plate,with less acquisition time and short depth of field distance.Up till now,there is lack of application in measuring moving objects with a long depth of field.For this reason,a set of PDV based on all fiber structure and upper computer demodulation software based on LabWindows are built.It uses a laser module with 15 kHz line width and 1550.12 nm wave length as light source,an aspherical lens with 300mm working distance as probe.Speed measurement for rodless cylinder slider with a moving distance of 1.33 m and a maximum speed of 14 m/s.Through many experiments,the whole time velocity diagram of rodless cylinder is obtained.Moving distances calculated by integration are in consistent with the actual one,the average relative error of which is -0.5266%.The experimental result shows that PDV has a strong robustness,and an interference signal with SNR above 16 dB,even the coupled signal power is low.While there is a stable atmosphere,such PDV can be used in measuring moving objects with large depth of field.