<p>The chain conformation of polymers in binary solvent mixtures is a key issue in the study of functional soft matter and lies at the heart of various applications such as smart soft materials. Based on a minimal lattice model, we employ Monte Carlo (MC) simulation to systematically investigate the effects of solvent qualities on the conformation of a single homopolymer chain in binary mixed solvents. We also perform calculations using a Flory-type mean-field theory. We focus on how the introduction of a second solvent B affects the dependence of chain conformation on the quality of solvent A. We mainly examine the effects of the composition of solvent B, denoted by <i>x</i>, and the interactions between the two solvents. First, when <i>x</i> is low, the mean-square chain radius of gyration exhibits qualitatively similar behaviors to those in an individual solvent A, with a slight chain contraction when solvent A is very good. Second, in equal-molar mixtures with <i>x</i>=0.5, a homopolymer chain collapses when solvent A is either poor or very good, while expands at intermediate qualities. Lastly, at large <i>x</i>, a chain undergoes a coil-to-globule transition with the increasing quality of solvent A when solvent B is good, but mainly adopts the collapsed conformation when solvent B is poor. Our findings not only improve our understanding on the chain conformation in binary solvent mixtures, but also provide valuable guidance on the rational design of stimuli-responsive polymeric materials.</p>