It has been found that the attention SNARC effect is stable in the cognitive processing of numbers, but there is no research to explore whether the mixed presentation of numbers and letters can affect the attention SNARC effect. The experiment of this study adopts the dot-probing paradigm to present the subjects with a mixture of numbers and letters in equal proportions, and requires the subjects to respond to the presented detection stimulus, and further investigates the influence of the mixture of numbers and letters in equal proportions on the attention SNARC effect and its mechanism. The results showed that no SNARC effect was observed in the processing of numbers and letters when numbers and letters were mixed in equal proportions. The results show that the SNARC effect of attention is significantly affected by the mixing of numbers and letters.