Soil respiration is an important index to reflect soil quality and nutritional properties. However, these characteristics of latosol orchards of guava (Psidium guajava L. Pearl) in the south subtropics are not fully understood. In the present research, the effects of Stylo grass [Stylosanthes guianensis (Aubl.) Sw.] on soil respiration in guava orchards of latosol were studied. There were four treatments, namely, clean tillage, natural grass growth, Stylo grass 'Ubon' and 'Reyan No. 2'. Soil respiration was monitored from December 2018 to November 2019 by using a soil CO2 flux system (LI-8100A, LI-COR, Lincoln, NE). Results showed that Reyan No. 2 had the best promoting effect on soil respiration in orchards, followed by Ubon and natural grass growth. The relationship between soil respiration and soil temperature of 5-cm soil layer followed highly significant power function pattern for Stylo grass treatments (p < .01). The temperature sensitivity (Q10) of Reyan No. 2 was highest (1.75), followed by Ubon (1.46). Soil water, instead of temperature, was found to be the main factor of soil respiration in the grass orchard of latosol. This study proposes the main limiting factors of soil respiration in latosol orchards and recommends Reyan No. 2 as a grass variety for soil improvement. The finding has also enriched the theory and practice of soil improvement in latosol orchards. The higher Q10 (1.75) of Reyan No. 2 as obtained in this research may also have a certain effect on the soil carbon cycle of grass orchard of latosol. [ABSTRACT FROM AUTHOR]