Abstract　 　 
The observed relation between gas surface density and star formation rate, the Schmidt-Kennicutt relation, is one of the most critical links between star formation and galaxy evolution. This relation is tight when properties are averaged over kpc, but breakdowns at scale of giant molecular clouds (GMCs). To understand the physical connection between local variations in star formation on GMC scale and the tight correlation at kpc scale, spatially and temporally resolved data covering a wide range of linear scale are needed. To investigate star formation in a variety of environment,we have used the Spitzer surveys of the Large Magellanic Cloud and Magellanic Bridge to identify massive young stellar objects (YSOs), estimate the instant star formation rates (SFRs), and compare to that estimated from H-alpha and 24 micron luminosities, i.e., SFRs averaged over the last 20 Myr. We have also used SINFONI near-IR integral field spectra, in combination with 2MASS+UKIDSS near-IR and Spitzer GLIMPSE+MIPSGAL mid-IR imaging surveys, to study massive star and YSO contents in mini-starbursts W31 and W43 in the Galaxy. Through detailed examination on star formation in GMCs at different metallicity and galactic environment, we can better understand the physics connecting star formation and galaxy evolution.