As　physical　exercise　benefits　both　physical　and　psychological　health　of　college　students,　it　is　important　to　promote　the　habit　of　physical　exercise　among　them.　This　study　adopted　the　Health　Action　Process　Approach　(HAPA)　model　to　understand　the　exercise　intention-action　link　and　determine　the　moderating　role　of　self-efficacy.　We　recruited　242　students　from　a　university　in　China　and　asked　them　to　complete　a　six-wave　survey.　The　survey　results　indicated　that　exercise　intention　was　positively　related　to　both　coping　planning　and　action　planning,　which　pave　the　way　to　performing　the　action　of　exercise.　However,　such　mediation　effects　varied　under　conditions　of　self-efficacy.　Participants　with　high　self-efficacy　exhibited　stronger　relationships　between　intention　and　planning,　and　between　planning　and　action.　The　study　results　suggest　that　planning　has　a　time-lagged　mediation　effect　in　the　relationship　between　intention　and　action.　Additionally,　the　findings　shed　light　on　the　moderating　role　of　self-efficacy,　which　can　be　useful　in　developing　health-promotion　strategies　for　college　students.