Ultrashort fiber lasers with GHz repetition rate have already demonstrated their applications in laser communication, advanced manufacturing, astronomical and THz detection, et al, due to their advantages of large number of pulses per unit time, wide spectral coverage and narrow pulse duration. However, the main difficulty is how to yield pulses with duration less than 50fs and above 1GHz repetition rate at the same time. A 1.003GHz repetition rate Yb-doped fiber laser was built with 48.8fs pulse duration by using nonlinear polarization rotation mode locking (NPR). In our approach, WDM-Collimator was employed in order to shorten the length of the cavity. This fiber laser had the shortest output pulse duration among all reported Yb-doped fiber lasers with fundamental repetition rate above 1GHz. Finally, the laser was integrated into a prototype, which effectively reduced the manufacturing cost and improved the stability. The laser is expected to promote the industrialization and commercialization of high repetition rate fiber ultrashort pulse lasers.