For expansive soil slopes, the primary failure mode is surface- or shallow-layer slide, which can occur easily under repeated rainfalls. In this investigation, a field testing program is implemented on five expansive soil slopes with different inclination subjected to artificial rainfalls, against which a numerical model is calibrated. Hydro-mechanical analysis is then conducted to estimate the factor of safety for expansive soil slopes with different pattern of fissures. A high slope inclination can increase the surface runoff, although the factor of safety decreases. It is of significance to minimize the amount of rainfall infiltration through desiccation cracks, since the increase in volumetric water content from rainfall events is more detrimental to reduce the unsaturated shear strength of soil. A conceptual framework is proposed to apply a drip irrigation system for expansive soil slopes. The volumetric water content can be maintained above a critical level to avoid the initiation of desiccation cracks. In the end, design parameters for the drip irrigation system are optimized. •Expansive soil slope fails due to rainfall infiltration through desiccation cracks on the slope surface.•Correlation between rainfall infiltration, slope inclination and slope height is established.•There is a trade-off between slope inclination, rainfall infiltration and factor of safety.•Steep slope is suggested to maximize the surface runoff.•Drip irrigation can control the water content of expansive soils to avoid the initiation of desiccation cracks.