The lymphatic system is an important defense function system in the human body. It is also critical to humoral homeostasis. Local dysfunction will cause edema, immune deficiency, and a high incidence. There are intraluminal valves in the lymphatic system, which allows the lymph fluid to flow to the large veins and heart. It has three major immune functions. First, it can resist bacterial viruses and protect the human body from disease attacks. Secondly, it is supplemented by lymphocytes to remove the products produced by metabolism. In the end, The damaged organs and tissues are repaired by lymphocytes to restore normal physiological functions. The lymphatic system does not have the same pump as the heart of the blood circulatory system. The driving of lymph is mainly done by the spontaneous contraction of the lymphatics (the lung lymphatic system is compressed by the alveoli). The autonomic contraction cycle of lymphatic vessels is caused by the increase of Ca²⁺ in lymphocytes, and the contraction drives the fluid to produce shearing force. The shearing force produces nitric oxide synthase (eNOS) in lymphatic endothelial cells, and eNOS increases NO and increases NO. Decreasing Ca²⁺ relaxes lymphatic vessels, fluid shear rate decreases after lymphatic vessel relaxation, eNOS decreases, NO decreases, Ca²⁺ increases, lymphocytes contract, and a new cycle begins. It can be seen that the concentration of NO and its distribution play a key role in the contraction of lymphatic vessels. Obviously, export pressure affects the shear rate of fluid in the lymphatics, which in turn affects the concentration of NO and the contraction of lymphatic vessels. To investigate the effect of lymphatic outlet pressure on lymphatic vessel contraction, we established a lattice Boltzmann model to simulate the initial lymphatic vessels embedded in porous tissue and the collecting lymphatic vessels with two pairs of valves. The valve is the main source of NO. Once contraction begins, the contraction is spontaneous, self-sustaining, and the system exhibits non-linear dynamics. This model can reproduce NO and The interaction of Ca²⁺ and the spontaneous contraction of lymphatic vessels, and the distribution of NO under different outlet pressures and their average values were studied.