Graphene-like IIA-VI monolayer monoxides have been predicted to be novel two-dimensional (2D) materials with intrinsic bandgap, which makes them promising prospect for electronics and optoelectronics applications. In the field of microelectronics, heat dissipation is considered as the bottleneck that limits further development. Thus, the effective regulation in thermal transport is of great interest for designing novel devices. A systematic study in this work is carried out by first-principles method to explore thermal conductivity of these monoxides under strain. Compared with that of minimum strained MgO, CaO, SrO and BaO, the maximum thermal conductivity is increased by 3.25, 3.07, 1.50 and 1.53 times respectively under tensile strain. Detailed analysis shows that the weakened phonon-phonon scattering strength is the behind physical mechanism. It is also found that the tensile strain aids to improving the stability. Our work provides an attractive platform by studying the thermal transport of these monoxides under strain, suggesting the possible applications of these monolayers in novel modern devices.© 2020 IOP Publishing Ltd.