PSR B1821-24A is located in the dense globular cluster M28 and is known to exhibit complex timing behavior. The nature leading to the complex timing behavior become an interesting question. We present 33 years of timing observations of this pulsar and investigate various effects that could be responsible for the observed spin behavior. We analyzed the noise properties, and modeled the pulse arrival times as a series of frequency derivatives, and searched for any unknown glitches. In my talk, I will share our exploration of this pulsar’s timing behavior.