This paper introduces the progresses and evolution of stormwater management and planning in urban watersheds in Canada, as well as the wet weather flow management policies, principles, and standards in Toronto, the largest city in Canada. A comparison study has been conducted to provide new ideas and insights for stormwater management in China through comparing these policies, principles, and standards with the technical guideline for sponge city development in China. Some problems of the technical guideline have been pointed out, which include the lack of verification schemes for LID(low impact development)design, and the failure of consideration of precipitation.