Floating-point programs are challenging for symbolic execution due to the constraint solving problem. To investigate the effectiveness and limitations of the existing methods, we conduct the first empirical study in this paper on five existing symbolic execution methods for floating-point programs. We have implemented the existing methods on the state-of-the-art symbolic execution KLEE and use the real-world representative floating-point programs as the benchmarks, which are used to evaluate the existing methods with respect to code coverage and bug finding. The results indicate that the existing methods complement each other in bug finding. Based on the findings of the experimental results, we propose synergizing the existing methods to improve symbolic execution’s effectiveness. The experimental results demonstrate our synergic method can detect more bugs.