In　this　paper,　the　effects　of　quartz　fibers　on　the　resistivity,　complex　permittivity,　complex　permeability,　and　S-parameters　of　high-alumina　cement　pastes　are　investigated.　Meanwhile,　the　change　of　microstructure　after　adding　quartz　fibers　were　analyzed　by　mercury　intrusion　porosimetry　(MIP)　and　scanning　electron　microscope　(SEM).　The　results　show　that　with　the　increase　the　content　of　quartz　fiber,　the　real　part　of　complex　permittivity　decreases,　while　the　imaginary　part　of　complex　permittivity,　dielectric　loss　tangent,　and　resistivity　increased.　At　the　same　time,　there　are　more　small　pores,　and　the　interface　situation　is　more　complicated　after　adding　quartz　fiber.　Therefore,　the　reflectivity　decreases　and　the　absorptivity　increases,　but　the　scope　of　increase　in　the　absorptivity　is　smaller　than　the　decrease　in　the　reflectivity,　resulting　in　an　increase　in　the　transmittivity.　When　the　content　of　quartz　fiber　is　0.15,　0.30,　0.45,　and　0.60%,　the　average　transmittance　of　high-alumina　cement　paste　is　increased　by　3.69,　6.18,　15.51,　and　21.03%　respectively.　It　is　indicated　that　the　quartz　fibers　can　improve　the　wave　transmission　properties　of　the　high-alumina　cement　paste.　Copyright　©　2022　Yang,　Li,　Liu,　Li,　Jin　and　Li.