The invention provides a degradable material for oil and gas field operation and a preparation method thereof. The preparation method of the degradable material for oil and gas field operation comprises the step of carrying out melting mixing reaction on two, three, four, or five polymers of polyglycolic acid, polycaprolactone, polylactic acid, poly butylene succinate and poly-3-hydroxybutyrate and a chain extender, so as to obtain resin alloy, namely, the degradable material for oil and gas field operation. The degradable material for oil and gas field operation can be prepared into shapes such as pieces, powder, particles and balls, or can be prepared from one of polyglycolic acid, polycaprolactone, polylactic acid, poly butylenes succinate and poly-3-hydroxybutyrate into shapes such as pieces, powder, particles and balls through the method, is used for temporary plug and filtration reduction for protecting a reservoir, and temporarily plugging shot holes, constructed layer sections, and the like during various operation (drilling, well completion, well repair and acid fracturing) in the oil and gas field, and has the advantages of being completely degradable and harmless to the stratum.