The invention discloses a manufacturing method of an embedded cavity structure for a monofilm layer LTCC (Low Temperature Co-Fired Ceramic) and belongs to the field of micromechanical structure manufacturing. The manufacturing method comprises the following steps: carrying out primary lamination treatment on a cavity basal layer and a cavity wall layer which are superposed, singly carrying out lamination treatment on a cavity film layer, carrying out stacking and lamination treatment on the cavity basal layer and the cavity wall layer which are subjected to the primary lamination treatment and the cavity film layer subjected to the lamination treatment, and finally carrying out co-firing treatment on a stacked substrate subjected to conjunctive lamination treatment by applying an LTCC co-firing furnace. The manufacturing method has the advantages that a sacrificial layer material is not needed in the manufacturing phase of the embedded cavity; by utilizing the shrinkage mismatching property expressed between an LTCC monofilm layer ceramic sheet after lamination by different pressures and a plurality layers of basal plate in the sintering ceramic forming phase and controlling the pressure intensity applied to the monofilm layer in the lamination phase, the shrinking rate of the monofilm layer is larger than that of the plurality layers of basal plate, and thus a smooth monofilm layer surface is realized.