The polyethylene (PE) industry is in a stage of rapid development. However, PE dust floating in the air is frequently associated with unexpected explosions. To find a proper way of preventing and mitigating the potential of PE dust explosion, a study was carried out in which (NH4)2CO3 and SiC were used for the first time to suppress PE deflagration flames. In a Hartmann tube apparatus, PE deflagration flame propagation in the presence of (NH4)2CO3 and SiC powders as the suppressant was observed. The suppression effects of these two powders at different mass fractions were compared. The results showed that flame propagation velocity and acceleration decrease with increasing mass fraction of (NH4)2CO3 and SiC. Through XRD, FIRT, TG-DSC, GC–MS and sensitivity test, explosion products and combustion reactions were characterized and the PE explosion suppression mechanisms of (NH4)2CO3 and SiC for PE were compared and investigated. PE explosion is suppressed by SiC physically by reducing temperature and pressure of explosion combustion, while the explosion combustion of PE was suppressed by physical and chemical effect of (NH4)2CO3. As a result, (NH4)2CO3 is better able to suppress explosion flames. The study provides a theoretical and practical basis for the prevention and control of explosion fire accidents in the polyethylene industry.