An apparatus and a method are provided for transmitting data in an electronic device. A method for processing data in an electronic device includes in network connection, determining whether to send a packet of a first Maximum Transmission Unit (MTU) value that is preset, a destination node, responsive to the packet of the first preset MTU value not being transmitted to the destination node, measuring an optimal MTU value in an Internet Protocol (IP) layer or an application layer, and changing the first preset MTU to the measured optimal MTU value.