Building practical devices from 2D semiconducting crystals and their heterostructures is an intensively pursued research area. Currently, chemical vapor deposition (CVD) of monolayer semiconductors is the only practical way to synthesis these materials at industrial scale. However, elastic properties of CVD-grown 2D semiconductors and their heterostructures have not been measured, although their less-defective, exfoliated counterparts have. In this work we experimentally and theoretically characterized the elastic modulus of CVD-grown MoS2, WS2 as well as their heterostructures with each other and with graphene. The 2D moduli of heterostructures are slightly lower than the sum of 2D modulus of each layer, but comparable to the corresponding bilayer homo structures, implying similar interactions between hetero monolayers compared to between homo monolayers. The interlayer coupling of different bilayer homo or hetero structures is also qualitatively compared by introducing a sliding coefficient. Our results provide calibrated values of elastic modulus of these structures for various applications, especially in flexible electronic and mechanical devices.