The research aims to 1) develop liquefied petroleum gas (LPG) and smoke detectors for emergency alerts 2) to develop a manual for the use of liquefied petroleum gas (LPG) and smoke detectors for emergency alerts by applying microcontrollers to control and process. In the experiment, liquefied petroleum gas (LPG) and smoke were detected by using liquid petroleum gas and smoke leakage sensors. When the amount of liquefied petroleum gas and smoke exceeds the concentration level in the air, liquefied petroleum gas and smoke detectors send a buzzer alert signal. The results showed that the system could effectively display the alarm situation of the sound from the buzzer and alert SMS to the user or the relevant person. The performance test result of the liquefied petroleum gas detector are as follows: 1) the fastest detection of the liquefied petroleum gas in 05.47 seconds, 2) the detection of the volume of smoke from the burning of paper in 14.04 seconds, 3) the detection of the smoke volume of electrical wires in 17.21 seconds, 4) the detection of the smoke volume of wipes at 22.34 seconds, and 5) the slowest detection of the amount of smoke of the document file at 28.90 seconds and  have to develop a user manual of liquefied petroleum gas (LPG) and smoke detectors for emergency alerts of efficiency.