In recent years, heterogeneous parallel architecture has become an important development trend of supercomputer because it mitigates the problem of increasingly high power consumption. As a high performance and power efficiency accelerator, GPU (graphics processing unit) has been extensively used in HPC (high performance computing) area. However, the inherent unreliability of the GPU hardware deteriorates the reliability of supercomputer. Presently, most research of FT (fault-tolerance) techniques for CPU-GPU heterogeneous system isolates the GPU from the system, and does FT work for it at the granularity of a single GPU invocation. This paper proposes a new Lazy FT method for CPU-GPU heterogeneous system, introduces a FT framework and its constraints based on directives, and demonstrates the validity of the Lazy FT method. The experimental results show that, compared with existing FT methods, the cost of LazyFT is very cheap.