To　comprehensively　investigate　the　effects　of　secondary　ground　waves　(SGWs)　induced　by　the　vibration　of　receiver　piles　(RPs)　in　layered　soils　on　the　pile-pile　horizontal　vibration　(PPHV),　a　simplified　mechanical　model　for　frequency-domain　analysis　of　PPHV　is　proposed.　This　proposed　model　is　based　on　layered　Pasternak　soils　and　elastic　Euler-Bernoulli　beam　theory,　incorporating　the　effects　of　axial　loads　and　SGW.　Firstly,　the　horizontal　displacements　(HDs)　and　the　internal　forces　of　the　source　pile　(SP)　are　obtained　using　the　differential　transformation　method　combined　with　the　continuity　boundary　conditions　(BCs)　at　the　pile-soil　interface.　Secondly,　considering　the　influence　of　the　vibration　of　the　SP　on　the　RP,　a　horizontal　vibration　analysis　model　for　the　RP　is　established,　followed　by　the　derivation　of　an　analytical　solution　for　the　horizontal　dynamic　response　(HDR).　Furthermore,　to　consider　the　influence　of　SGWs　induced　by　the　vibration　of　the　RP　on　the　HDR　of　the　SP,　an　improved　analytical　solution　for　the　HDR　of　the　RP　is　obtained.　Finally,　based　on　the　definition　of　the　dynamic　interaction　factor,　the　pile-pile　horizontal　dynamic　interaction　factor　(PPHDIF)　is　derived　and　its　rationality　is　validated　by　comparisons　with　existing　solutions.　Parametric　analyses　are　performed　to　explore　the　effects　of　soil　shear　deformation,　pile-soil　modulus　ratio,　and　axial　loads　on　the　PPHDIF.　The　results　provide　theoretical　guidance　and　references　for　the　dynamic　design　of　pile　groups　in　engineering　practice.