ILSP (Interlaced inner and outer Loop Software Pipelining) is an efficient algorithm of optimizing operations in the nested loops. To ensure the ILSP has a good time efficiency and a good space efficiency, there must be an efficient nested control mechanism to support the algorithm. Our control mechanism is realized by hardware, it avoids adding many extra instructions and minimises the II (Initialization Interval) of each loop in the nested loop. In cooperation with the compiler, our nested loop control mechanism can efficiently support the software pipelining of the nested loop, and can ensure the ILSP has a high speedup and a low space cost.