The invention discloses a device and a method for processing interlaced line-crossing stereoscopic composite video signals. The method comprises the following steps: firstly, finishing decoding interlaced crossing stereoscopic composite video signals in a 3D (three-dimensional) composite video decoder; then, converting the format of the composite video signals into the format of 16-bit YUV4:2:2; controlling the storage and read-out by an SDRAM (synchronous dynamic random access memory) frame memory; passing through two alternative multiplexers, so that the left-channel video is always outputted as an odd field and the right channel video is always outputted as an even field; and finally, outputting to an OLED (organic light emitting diode) micro-screen and displaying after image zooming and OSD (on-screen display) superposition. Upon the premise that only one 32-bit frame memory SDRAM is used, the invention can achieve the frame frequency elevation to the stereoscopic composite video signals and perform the function of decoding 3D composite video signals at the same time, thereby increasing the utilization rate and bandwidth of SDRAM and the integration of the device.