The study of plant community assembly is integral for understanding species coexistence and biodiversity maintenance, and it has long been a central issue in community ecology. The mechanistic theories of community assembly generally fall into two classes: niche theory and neutral theory. Although validation studies of niche theory and neutral theory have achieved great advances in recent years, some difficulty remains in understanding the mechanisms of local community assembly. Advances in statistics and theory make it possible to infer community assembly mechanisms based on functional traits and phylogenetic structures, by testing the dispersion patterns of trait and phylogenetic distance among co-occurring species. Both trait and phylogenetic community methods share the same conceptual approach. The observed distribution of either traits or phylogenetic distances within a local community is compared to a null expectation generated by drawing species at random from a regional pool of potential colonists. Deviations from the null expectation can be used as evidence for a number of ecological processes in the assembly of the local community. Both the approaches for measuring species differences can be aggregated at the community level to summarize the degree to which the constituent species differ in terms of their function, niche, or evolutionary history. However, traits and phylogenies provide different, and perhaps complementary, information in understanding patterns of community assembly. To adequately test assembly hypotheses, a framework integrating the information provided by functional traits and phylogenies is required. In addition, many biotic and abiotic factors (competition, facilitation) control community assembly. Different factors shape the distribution and abundance of species at different spatial and temporal scales. Multiple processes, including dispersal limitation based on neutral theory, and environmental filtering and limiting similarity based on niche theory, may simultaneously affect community assembly. The relative importance of these processes will differ among communities. The same process may cause opposing diversity patterns, and the same pattern may result from different processes. Therefore, it is important to simultaneously consider multiple methods and influence factors when exploring mechanisms of plant community assembly, predicting plant response to disturbance, and understanding biodiversity maintenance. In this paper, we provide a review of the histories, theories, methods, and new advances in community assembly explanations. We discuss ways to explain plant community assembly mechanisms by integrating functional trait and phylogenetic structure methods. We argue that time scale, number and type of traits, intraspecies trait variation, and interference should be considered in a study of community assembly, but spatial scale, environmental factors, and vegetation type need not be considered.