This　study　focuses　on　the　calcareous　cemented　conglomerate　on　the　side　wall　of　the　Zhoukoudian　Ape　Man　Cave　site　in　Beijing.　We　analyzed　the　change　patterns　of　cracks　in　grotto　rock　under　natural　conditions　using　statistical　analysis　of　continuous　monitoring　data　from　12　rock　fracture　measurement　points　for　7　years　and　environmental　monitoring　data.　The　results　indicated　that:　(1)　Under　natural　conditions,　rock　fracture　width　exhibited　seasonal　and　periodic　variations,　which　can　be　predicted　using　autoregressive　integrated　moving　average　(ARIMA)　model.　The　ARIMA　(2,　1,　1)　model　has　the　highest　fitting　accuracy.　(2)　The　width　of　rock　fractures　showed　a　negative　correlation　with　ambient　temperature　and　relative　humidity,　with　a　stronger　correlation　with　temperature.　Changes　in　fracture　width　lagged　behind　changes　in　temperature　and　relative　humidity,　with　a　higher　lag　correlation　and　shorter　lag　time　for　temperature　compared　to　relative　humidity.　(3)　The　degree　of　correlation　and　lag　correlation　between　rock　fracture　width　and　ambient　temperature　followed　the　trend　of　room-temperature　＞　high-temperature　＞　low-temperature　＞　extremely-low-temperature.　The　lag　time　followed　the　trend　of　extremely-low-temperature　＞　low-temperature＞high-temperature.　Additionally,　more　stable　relative　humidity　of　the　surroundings　indicated　a　higher　correlation.　(4)　At　a　constant,　the　width　of　rock　fractures　increased　gradually　over　time,　following　an　approximate　exponential　growth　or　asymptotic　distribution.　(5)　At　the　same　temperature,　more　stable　relative　humidity　corresponded　to　a　slower　increase　in　rock　fracture　width　over　time.　Under　natural　conditions,　lower　ambient　temperatures　led　to　a　rapid　increase　in　rock　fracture　width　over　time.　These　findings　enhance　our　understanding　of　the　expansion　patterns　of　cracks　in　grotto　rock　under　natural　conditions.　Moreover,　they　provide　a　reference　framework　for　predicting　crack　changes　in　the　preventive　conservation　of　ancient　rock　sites,　caves,　and　stone　carvings　in　temperate　monsoon　climate　regions.　©　2024　Biodiversity　Research　Center　Academia　Sinica.　All　rights　reserved.