As　a　zero-carbon　fuel　and　hydrogen　carrier,　ammonia　has　received　much　attention　for　its　excellent　carbon　reduction　potential.　To　explore　the　feasibility　of　zero-carbon　ammonia　as　fuel　for　in　small-scaled　Wankel　rotary　engines,　a　computational　fluid　dynamics　model　coupled　with　a　kinetic　mechanism　was　established　and　validated.　It　is　found　that　the　fuel　mixture　cannot　be　ignited　when　the　hydrogen　substitution　ratio　(HSR)　is　less　than　5%.　Increasing　HSR　shortens　flame　development　period　and　intensifies　combustion.　When　HSR　is　greater　than　12.5%,　the　fuel　can　be　burned　up,　and　the　position　of　peak　heat　release　rate　remains　close　to　20°EA　aTDC.　Elevated　HSR　leads　to　higher　NO　emissions　but　lower　NO2　and　N2O　emissions.　As　expected,　advancing　ignition　timing　(IT)　significantly　enhances　combustion　efficiency　and　reduces　emissions.　Advancing　the　IT　results　in　a　slight　increase　in　the　unburned　area　at　the　rear　of　combustion　chamber,　coupled　with　a　rapid　decrease　in　the　unburned　area　at　the　front,　collectively　reducing　unburned　fuel.　When　IT　is　advanced　from　−5　to　−35°EA　aTDC,　emissions　and　performance　increase　rapidly,　whereas　when　advanced　to　−45°EA　aTDC,　both　are　nearly　unchanged　and　combustion　efficiency　decreases.　©　2023　Elsevier　Ltd