The research investigated the influences of international students' perceived online learning environments, self-efficacy, and online interaction on their online learning achievement, as measured by these students' self-reported development of "generic skills," "research capacities," and "Chinese proficiency and global abilities." Data were generated by a nationwide survey involving 1,010 international students across disciplines at 41 universities in China. The SEM analysis showed that among all factors directly and positively supporting international students' learning achievement, the two online environmental factors, i.e. "accessibility" to online learning resources and opportunities for "knowledge acquisition," presented the strongest effects. The mediation analysis showed that through interaction, environmental "interactivity" had significant and positive indirect influences on learning achievement; and through self-efficacy, "knowledge acquisition" had significant and positive indirect influences on learning achievement. The SEM analysis also revealed a significant negative influence of environmental "flexibility" on international students' "generic skill" development. Possible explanations for the results were proposed. Implications of the results were discussed to support the sustainable development of online international education.