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We report results of our recent study onpresent a comprehensive study on in-plane thermal conductivity and thermoelectric properties in high quality single crystals Sr₂IrO₄ with a Neel temperature at 240 K. We observe that the temperature dependence of thermal conductivity κ displays a sharp peak at around 10 K with its max value as high as 400 W/Km, yet little magnetic field dependence up to 14 T in all temperature from room temperature down to 4 K. This is in contrast to the Seebeck coefficient S_xx of which magnetic field dependence closely tracks that of the magnetization until its magnitude quenches to zero abruptly as temperature is lower below approximately 50 K. The new results of the thermal properties provide more insight into the physics of the iridate, especially spin degrees of freedom and phonons, which will be discussed along with other physical properties.