To investigate the coupling mechanisms between the functional traits of urban park trees and their multidimensional ecological benefits, and to elucidate the regulatory pathways through which tree species composition influences these ecological benefits, a total of 3 077 trees in Baling Lake Fitness Park were analyzed. The i-Tree Eco model was employed to access the benefits related to carbon sequestration, oxygen release, air purification, and rainwater interception. Multiple regression and variance partitioning analysis were conducted to explore the relationships between ecological benefits and functional traits. The annual ecological benefits of the park were estimated at 502 300 yuan, with the following distribution: carbon sequestration (79.83%, 401 000 yuan) > oxygen production (17.54%, 88 100 yuan) > air purification (2.55%, 12 800 yuan) > rainwater interception (0.08%, 400 yuan). Carbon sequestration demonstrated a highly significant stepwise regression relationship with mean diameter at breast height (Dm), leaf phosphorus content (Leaf-P), and height above first branch (HFBm) (adjR2=0.767, p<0.001), with Dm contributing the most (76.26%), followed by Leaf-P (15.29%). Air purification showed a highly significant regression relationship with mean tree height (Hm), mean crown width (CWm), Leaf-P, and height to crown base (HCBm) (adjR2=0.877, p<0.001), with Hm (41.03%) and CWm (39.20%) being the primary contributors.Rainwater interception was significantly related to Hm (adjR2=0.273, p<0.05). Biomass traits (Dm, Hm, CWm) are critical factors influencing ecological benefits, interacting synergistically interacting with physiological traits such as Leaf-P. To optimize fitness park ecological benefits, it is recommended to prioritize planting large-DBH species (Euonymus maackii) to enhance carbon sequestration, combine tree species with large crowns and high Leaf-P (Platanus acerifolia) to improve air quality, and configure tree species with high growth potential in tree height (Firmiana simplex) to boost rainwater interception and oxygen release.