Acer laurinum (Sapindaceae) is a threatened tree plant species with least concern (LC) status. There is only limited information regarding the phenology of flowering and fruiting of this species. Along with the increasing damage to its natural habitat, not surprisingly, in the future, this status will be more threatened. Therefore, it is necessary to study the phenology cycle of this species for the purposes of further development. In order to achieve a continuous and sequenced observation, the study was conducted in a built environment, one of an ex-situ plant conservation site. Furthermore, the study also conducted to analyze the effect of the microclimate on this cycle. The study conducted with A. laurinum tree specimen planted in 1986 at Cibodas Botanic Gardens, Cianjur, West Java. The study used descriptive quantitative analysis based on the exploratory-inventory observation of flowering and fruiting phase data, and the microclimate conditions assessed from 2014 to 2015. The results showed that the flowering and fruiting occurred from early January to April, and at the end of the year, from September to December, along with the high level of precipitation of the periods. Even the other microclimate units also dynamically changed, but there were no significantly affected the flowering and fruiting phenology. The results suggested that these periods can be conducted seeds harvesting and (re)stock in order to achieve maximum results.