The formation is complex in Kumar iron mine in Luanxian of Hebei Province, hard and slipping, severe leakage and tectonic development (partial fault) are often met during drilling. Based on the previous drilling experience, drilling technical measures and drilling construction quality assurance measures were put forward to deep drilling in complex strata of more than 1000m. From aspects of the hole structure, flushing fluid selection, drilling equipment and drilling tool configuration, the processing methods for solving the problems in hard and slipping, broken and leakage as well as collapse blocking formations were put forward, by which the drilling construction environment, the preparation of broad-spectrum retaining agent, anti caving plugging agent and polyacrylamide flushing fluid were improved with higher drilling efficiency and safe well completion.