Sexual desire is a desire for sexual intercourse under certain conditions of sexual stimulation, including the desire for contact and excretion. Contact desire refers to the strong desire of men or women to have physical contact with the opposite sex. It ranges from kissing, hugging, touching, to physical or close proximity, to direct genital contact. In a functional sense, “contact” enhances sexual arousal and leads to orgasm through the accumulation of sexual excitement. The desire to excrete refers to the male sexual maturity, the testicles continue to produce sperm, the vas deferens is filled with semen, so that sexual sensitivity increases, and cause a special tension, resulting in a strong desire to excrete it. Excretion is the ultimate purpose of the sexual act and is an important factor in the production of sexual desire in men, while in women there is a far stronger “desire for contact” than in men. Sexual desire mainly depends on three factors: 1, the intensity of external sexual stimulation; 2, the sensitivity of receiving sexual stimulation; 3, the strength of the sexual physiological response. Sexual arousal refers to the process of sexual excitement in the sexual organs when the energy of sexual impulses accumulates to a certain degree and under appropriate conditions of sexual stimulation. Sexual arousal is formed by psychological and physiological conditioned reflexes and unconditioned reflexes. Unconditioned reflexes are instinctive behaviors determined by heredity and are untaught, while conditioned reflexes are linked to human consciousness, which is subordinated to the higher regulatory mechanism of the brain. Sexual desire in animals relies mainly on the lower senses of smell and touch. In humans, vision and imagination play an important role in sexual arousal. Of course, direct stimulation of sexually sensitive areas is most likely to cause sexual arousal. Sexual arousal begins by directing a person’s attention to sexual stimulation, which excites the reproductive organs and causes a series of reactions and changes in the body to prepare for the sexual act. Sexual arousal is formed by mental and physical conditioned and unconditioned reflexes. Conditioned reflexes are linked to human consciousness, which is subordinated to the higher regulation mechanism of the brain. Thinking occurs and develops mainly on the basis of vision and hearing, and vision, hearing and imagination play a great role in sexual arousal. Whether male or female, individual differences in sexual sensitivity are great, and this is greatly related to consciousness, perception, feelings, physical fitness, fatigue, and environment. Some people can cause a strong sexual response to weak sexual stimulation, while others need stronger sexual stimulation to cause a sexual response, resulting in the time required for sexual arousal also varies greatly, some only need a few minutes, some need several hours. Sexual desire and arousal play a very important role in a quality sex life. It is only when there is sexual desire that there will be an active and coordinated sexual process, and adequate sexual arousal will make it easier for both parties to reach orgasm together.