A built-in air pump for an inflatable body, comprising: a housing body and a panel, said panel being coupled to said housing body and defining an opening in fluid communication with an outer environment of the inflatable body; a main pump body coupled to said housing body and defining a first accommodating chamber, a first venting port, and a second venting port, said first accommodating chamber being in fluid communication with said opening, said first venting port and said second venting port; a main pump, located inside the first accommodating chamber; an air replenishing pump having an air replenishing pump body, said air replenishing pump body located adjacent to said main pump body, said air replenishing pump body defining a second accommodating chamber having therein said air replenishing pump; a first connecting member, located between said main pump body and said housing body to connect said main pump body to said housing body; a second connecting member, located between said air replenishing pump body and said housing body to connect said air replenishing pump body to said housing body; an air passage switch located in said first accommodating chamber, said air passage switch being moveable between a first position and a second position; wherein when said air passage switch is in said first position, said air passage switch, said main pump body, and said first venting port collectively define an inflation air passage; wherein when said air passage switch is in said second position, said air passage switch, said main pump body, and said second venting port collectively define a deflation air passage; and a controller in electrical connection with said air replenishing pump, said controller configured to activate said air replenishing pump based on a time determination. a housing body and a panel, said panel being coupled to said housing body and defining an opening in fluid communication with an outer environment of the inflatable body; a main pump body coupled to said housing body and defining a first accommodating chamber, a first venting port, and a second venting port, said first accommodating chamber being in fluid communication with said opening, said first venting port and said second venting port; a main pump, located inside the first accommodating chamber; an air replenishing pump having an air replenishing pump body, said air replenishing pump body located adjacent to said main pump body, said air replenishing pump body defining a second accommodating chamber having therein said air replenishing pump; a first connecting member, located between said main pump body and said housing body to connect said main pump body to said housing body; a second connecting member, located between said air replenishing pump body and said housing body to connect said air replenishing pump body to said housing body; an air passage switch located in said first accommodating chamber, said air passage switch being moveable between a first position and a second position; wherein when said air passage switch is in said first position, said air passage switch, said main pump body, and said first venting port collectively define an inflation air passage; wherein when said air passage switch is in said second position, said air passage switch, said main pump body, and said second venting port collectively define a deflation air passage; and wherein when said air passage switch is in said first position, said air passage switch, said main pump body, and said first venting port collectively define an inflation air passage; wherein when said air passage switch is in said second position, said air passage switch, said main pump body, and said second venting port collectively define a deflation air passage; and a controller in electrical connection with said air replenishing pump, said controller configured to activate said air replenishing pump based on a time determination.