Objective  Good building lighting condition is an important factor to ensure the hygiene of the room, improve the microclimate and the comfort of the living environment. Studying the impact of greening between buildings on the sunlight conditions of building and analyzing the influencing degree and specific influencing factors can be used to optimize the construction of plant community and improve green space environment and landscape in the residential areas.

  Method  Taking the green space between multi-storey residential buildings in Beijing as the object of the study, we used Photoshop, Image-Pro Plus and Rhino to calculate the crown porosity of plants and establish the models of plants and buildings; and Ecotect Analysis to simulate the lighting situation in Beijing. By analyzing the sunlight situation of the buildings on the north side of green space between the buildings in the Great Cold day, the paper explores various factors affecting the lighting of the buildings.

  Result  (1) Fifty species of woody plants commonly were used for greening in the study area. The proportion of arbors in the plant structure was high and the growth was at a high level. (2) The influence of building orientation on the lighting conditions was shown as follows: the building oriented south had the best lighting conditions; when the building skew angle was the same, influenced by the longitude and latitude of Beijing area, the building oriented east had better lighting conditions than the building oriented west. With the decrease of distance between buildings and the increase of the length of buildings, the sunshine hours of buildings decreased. (3) The general performance of the survey sample (85%) was that greening had seriously affected building lighting. The light surface of the sample building was generally affected by a large area, and the number of hours of sunlight was significantly reduced. The impact range was mainly concentrated on the 1−4 floor. The inter-building greening, which had a significant impact on building lighting, was mainly characterized by too many evergreen trees, too large plant size, and too close the distance between plants and buildings. When the distance between arbor and building was less than 5 m, it will have a great impact on the daylighting of the building; when it is longer than 5 m, it will still have an effect on the low floors of the building.

  Conclusion  (1) The basic characteristics of greening between buildings are that there are a great number of arbor species and small number of evergreen species, and the high-frequency application of small number of evergreen species is an important reason for the adverse effects of building lighting conditions. (2) The layout of the building itself will affect the lighting of the lower floors of the building. (3) The greening between buildings significantly affects the lighting of buildings. The main influencing factors are the plant volume, followed by the distance between plant and building, and the porosity of the plant canopy.