Massive molecular outflows are found to be commonly involved in processes forming massive stars, yet their basic properties are not well understood. Using observations from the Submillimeter Array, Spitzer Space Telescope, and complementary data from the Caltech Submillimeter Observatory 10.4 m telescope, we are carrying out a systemic study of massive molecular outflows at high angular resolution. Here I present showcases of jet-like and wide-angle outflows discovered in this study, as well as an evolutionary scenario concerning both morphology and energetics of massive molecular outflows.