We have experimentally investigated a number of properties of polyglycol in deepwater drilling fluids. Polyglycol retards pressure transmission from the fluid to the formation, and improves the shale cuttings recovery rate. Measurements of the electrokinetic potential (the zeta potential) and the clay particle size showed that the inhibiting effect of polyglycol involves adsorption on clay particles and plugging pores and cracks. Polyglycol inhibits gas hydrate formation, has good lubricity and low toxicity, and does not have a significant impact on the rheological properties of drilling fluids at low temperature.