In　this　work,　the　effect　of　directional　solidification　methods　on　solid　solution　windows　in　two　Ni-based　single-crystal　superalloys　is　investigated.　The　sample　prepared　using　the　liquid　metal　cooling　(LMC)　method　was　found　to　contain　smaller　dendrite　spacing,　lower　dendrite　segregation　and　eutectic,　and　a　smaller　size　of　γ′　phase　than　that　of　the　high-speed　rapid　solidification　(HRS)　method.　The　alloy-2　contained　higher　Cr,　Co　and　lowered　Re　exhibited　similar　dendrite　spacing　and　volume　fraction　of　eutectic,　and　the　lower　dendrite　segregation　and　smaller　size　of　γ′　phase　than　that　of　the　other　alloy-1.　The　solution　treatment　window　is　broadened　by　adopting　the　LMC　method　or　changing　the　composition　to　alloy-2.　This　is　mainly　realized　by　decreasing　the　lower　limit　temperature,　and　the　upper　limit　temperature　remains　unchanged.　According　to　the　eutectic　only　contains　the　melt　temperature,　a　similar　eutectic　is　responsible　for　the　unchanged　upper　limit　temperature.　At　this　state,　the　lower　bound　of　the　temperature　is　the　dissolution　of　the　γʹ　phase　in　the　dendrite　core.　The　smaller　size　of　γ′　phase　and　the　elements＇　partition　ratio　are　responsible　for　the　change　in　the　solid　solution　window.　©　2023　The　Authors