Immunological deficiency syndromes are illnesses or disorders where one or more immune system components have been lost or are defective. Specific infections and cancers are more prone to develop in patients with certain syndromes. Infection with the human immunodeficiency virus (HIV) most frequently increases the risk of developing Cryptococcal Meningitis (CM), which raises the mortality rate. Globally, there are thought to be 1,52,000 instances of Cryptococcal Meningitis among HIV/AIDS patients each year, which results in roughly 1,12,000 fatalities. The prevalence of cryptococcal infection has mainly remained constant in low- and middle-income countries despite the widespread use of antiretroviral therapy (ART), according to the Centres for Disease Control and Prevention (CDC). In this article, a nonlinear SIR mathematical model for co-infection of HIV and cryptococcal meningitis in immunocompromised individuals is formulated. The basic reproduction number (R_0) is calculated at disease free equilibrium point (E_0) by next gen matrix method. Disease-free and disease exist co-infection of HIV and cryptococcal meningitis model equilibria are found. Stability of co-infection of HIV and cryptococcal meningitis is discussed. The optimal control parameters u_1 represent the anti-fungal medicine treatment, u_2 represent CD4 testing (patients who have low CD4 levels) in HIV infected individuals, u_3 represent the screening for cryptococcal meningitis in HIV infected individuals, The control on treatment of cryptococcal meningitis infected individuals is u_4 and the control on treatment of cryptococcal meningitis in co-infected individuals is u_5. The HIV-CM model data is validated with Numerical simulation and ends with the conclusion