Reservoir damage mechanism has been widely studied， but the research of reservoir protection technology needs to be further in-depth. In view of the importance of reservoir protection， an acid soluble fiber is prepared by alkali oxidation method. By optimizing its particle size distribution and evaluating its acid solubility， it is confirmed that the combination of the fiber and rigid particles can achieve the purpose of reservoir protection. Drilling fluid additives （lubricants， fluid loss reducing agents and coating agents） for reservoir protection were optimized. The evaluation of lubricity， fluid loss reduction and rheology showed that the additives had good lubricity， fluid loss reduction and rheological properties. A drilling fluid system that can be used in reservoir was prepared. When acid soluble fiber and drilling fluid for reservoir are used at the same time， its rheological property can meet the construction requirements， with excellent salt resistance， good sedimentation stability and excellent reservoir protection performance. The field application in A coalbed methane well in Qinshui Block shows the excellent performance of acid soluble fiber and drilling fluid for reservoir， which is expected to be further applied.