Abstract: The delay time interval optimization of electronic detonator needs to consider the factors of the distance from the explosion center. Most of the existing research results are put forward for specific buildings， which need to solve the optimization problem of the delay time interval of the protected objects with different distance from the explosion center. Combined with a red sand rock excavation blasting project in China， the blasting vibration monitoring test of electronic detonator was designed and carried out， and the evolution law of peak particle velocity （PPV） and dominant frequency for seismic wave were analyzed. Based on the principle of linear superposition of seismic waves， the Fourier series fitting function of single hole blasting waveform was established by MATLAB program. The influence mechanism of number of superimposed waveforms and delay time interval （DTI） on the PPV of synthetic waveform （SW） was studied， and the optimization method of DTI for electronic detonator was proposed. The results show that， the PPV and predominant frequency of blasting seismic wave attenuate exponentially with proportional distance under the condition of red sandstone test site. The PPV of the SW tends to be stable when the number of superimposed waveforms reaches 23. The PPV of the SW is close to the PPV of the single hole blasting when the DTI is more than 2.6 times of the predominant period. The PPV of the SW may appear the minimum value or smaller value when the DTI is 0.4~0.6 times of the predominant period， but there will be interference superposition and vibration velocity enhancement when the DTI is about 1 times of the predominant period. The DTI optimization method can be used to calculate the optimal DTI between holes at any distance from explosion center.

Key words: electronic detonator, red sandstone, principle of linear superposition, predominant period, delay time interval