Pedestrian localization service is required in deep urban canyons. Many studies demonstrated the potentials of 3D building model to GNSS positioning, especially in city center areas. However, many narrow building canyon also contains dense foliage of street trees. This foliage not only strongly attenuates but also blocks the line-of-sight (LOS) visible GNSS signals. The number of the trackable satellites is hence greatly decreased to less than 4, which GPS receiver cannot provide positioning result. Even through the commercial GNSS receiver implemented strong filtering technique to provide the positioning solutions during the signal blockage, the results are usually erroneous. This research proposes to integrate a 3D map aided GNSS (3D-GNSS) with a smartphone-based pedestrian dead reckoning (PDR) to provide localization service in urban area with dense foliage.