The invention discloses a polyurethane electromagnetic wave absorbing layer for an anti-interference meter box. A preparation method of the polyurethane electromagnetic wave absorbing layer comprises the following steps: firstly, taking a proper amount of reactant; drying polyhydric alcohol for 30-60 minutes at a vacuum degree of 90-130 DEG C; adding iron plated graphene granules and a reinforcing agent according to set weight proportions, uniformly stirring, adding diisocyanate and an organic metal catalyst according to set weight proportions, heating to 80-90 DEG C, and continuously stirring to react for 10-20 minutes; and finally, adding an accelerant and a stabilizing agent according to set weight proportions, uniformly stirring again, pouring a mixture obtained through reaction into a special grinding tool of 2mm thick, curing for 3-4 days, and taking out, thereby obtaining a polyurethane wave absorbing material. The polyurethane-based wave absorbing layer disclosed by the invention consists of polyurethane and a wave absorbing agent. A sandwiched wave absorbing layer can be optimally combined according to specific application environments, and then requirements of wide absorbing frequency bandwidth, light weight and the like can be met.