Steady-state visual evoked potential (SSVEP)-based brain-computer interfaces (BCIs) have potential to realize a direct communication between the human brain and the outside environment in real-life situations. Recently, we proposed a stimulation approximation approach to increase the number of visual stimuli that can be realized on a computer monitor. In addition to the fundamental and harmonic frequencies, the refresh rate-based stimulation approach also elicits SSVEPs at other frequencies that are termed interference frequencies, which are derived from the interaction between the stimulation frequency and the refresh rate. This study aims to investigate properties of the interference frequency components, and propose to integrate the interference frequency components to enhance frequency detection of SSVEPs. The results suggest that the proposed approach could substantially improve the frequency detection accuracy of SSVEPs.