Phenotypic plasticity is the ability of an organism to express different phenotypes based on genetic basis under different biotic or abiotic environment. Aphids are small herbivorous insects, renowned as pests of economic significance in agriculture, horticulture and forestry. Aphids often exhibit diverse phenotypes, corresponding to the change of environmental factors, such as host plants, temperature, light and natural enemies. For example, phenotypic plasticity of aphids can be influenced by such factors of host plants as species and varieties, growth stages, and even amino acids composting of the host plants. High or low temperature can influence survival, fecundity and longevity, and determine the form of winged or wingless morphs of aphids. It had been proved by RAPD-PCR, SSR or other molecular markers that those phenomena were the integrated results of the host plants, temperature, species and clones of aphids. There were biological, ecological and genetic differences among the clones of different colours and among seasonal populations of aphids. It is helpful to analyze impacts of the above-mentioned factors either in research on the evolution or the control of aphids. In addition, issues that may be needed to study in the future are discussed at the last paragraph, including epigenetic regulation (DNA methylation, histone code, X-inactivation, genomic imprinting), the importance to study the winged aphids, and effects of global climate change on the evolution of aphids.