In recent years, inter-city commuting at the mega-region scale in China is becoming increasingly frequent. Compared to the commuting circles of international mega-cities, the characteristics of inter-city commuting and influencing factors in mega-regions remain to be cleared. Taking the Beijing-Tianjin-Hebei mega-region as an example, this study used origin-destination (OD) analysis and spatial statistical analysis based on GIS to investigate the spatial distribution of inter-city commuting with the location data of twin city commuting of Beike Net renters. Assisted by ordinary least squares (OLS) and geographically weighted regression (GWR) models with individual commuting time as the dependent variable, this study revealed the impact mechanisms under the combined effect of spatial variables and personal social attributes. The analyses showed that: 1) The inter-city commuting of the Beijing-Tianjin-Hebei mega-region is evidently along some corridors, concentrated in the east, southeast, and southwest commuting corridors. At the city level, Langfang and Tianjin are the main origins, while at the county level, the main commuting corridor is from the Yanjiao hightech zone to Beijing urban area. 2) The average inter-city commuting distance has exceeded the general metropolitan area boundary of 30-50 km. 3) The inter-city commuters account for more than 20% of the total commuting population located in the Yanjiao high-tech zone of Langfang City, Gu'an County, and Zhuozhou of Baoding City, forming a high-frequency commuting area-the Beijing commuter belt. 4) The GWR showed that spatial factors such as the difference in housing and salaries between the workplace and residential areas and the distance from the residence to the high-speed rail station have spatial heterogeneity effects on commuting time. The research found that the motivation for long-time inter-city commuting differs between cities. Some commuters in Tianjin are motivated by improving living quality and salaries, while some commuters in Langfang and Baoding are motivated by improving salaries and saving rent. The impact of individual attributes showed that the younger the age, the longer the commuting time. The results of this research provide a reference for the coordinated optimization of urban space layout and comprehensive transportation in mega-regions under the new urbanization strategy.