Whether an exotic plant can successfully invade a novel habitat depends on the invasiveness of the species (e.g., growth rate, propagule pressure) and the invasibility of the habitat (environmental factors). Mountain areas are difficult for exotic species to invade owing to high variation in environmental factors and the low propagule pressure of invaders. However, anthropogenic activities, particularly farming, frequently disrupt restrictions due to such factors, and subsequently benefit the range expansion of some exotic plants in mountain areas. The population of Galinsoga quadriradiata Ruiz & Pav., introduced from tropical America, has exhibited an explosive increase on Qinling-Bashan Mountain, mid-west China. However, the population growth dynamics and habitat preferences for this invasive species are unknown. In the present study, we conducted a field experiment and a sampling survey to determine the population growth dynamics and habitat preferences of G. quadriradiata. The field experiment was conducted in Xunyangba (Ankang, Shaanxi) beginning in late May 2014, with 12 1m × 1m plots in 4 sites of farmland which were in close proximity to each other. The coverage, height, number of inflorescences, and seed production of G. quadriradiata were measured or counted in each plot every 15-20 d until mid-September, by which time all the plants had died. The sampling survey was conducted in Qinling-Bashan mountain in July, 2014. In total, 90 1m × 1m plots at 30 sites were established with different altitudes, slopes, and aspects. The frequency, density, and height of G. quadriradiata were measured in each plot. Environmental factors, soil compaction, altitude, and slope were measured. A repeated-measures ANOVA (GLM-RMANOVA) was used to determine the population dynamics of G. quadriradiata within a complete growth cycle. PCA and multivariate analyses were used to detect the influence of environmental factors on the population characteristics of G. quadriradiata. Our results show that the population density of this invasive species reached 300 individuals/m², the average seed production was 675 seeds per individual, and the seed production of the whole population was 45,619 seeds/m² within one generation. This indicated that this high level of propagule pressure could provide sufficient seeds for a successful invasion in the study area. The population density decreased with time following a logistic pattern, and its mortality rate reached the highest level during the transition between vegetative growth and maturity. This suggests that G. quadriradiata may exhibit an inverse density-dependent effect during population growth. The result of the field survey shows that the frequency of G. quadriradiata in the local plant community is positively related to soil compaction, but negatively related to slope. This information is useful to predict its invasive tendency in the future. To summarize, G. quadriradiata would be a successful invader in habitats on Qinling-Bashan Mountain due to its high invasion potential; therefore, measures for controlling the an invasion of this exotic species are urgently needed.