Dielectric elastomers (DEs) are widely studied as artificial muscles due to their large actuation strain and fast electromechanical response. Currently, the commonly used acrylate DEs require high prestretching and are subjected to a high actuation electric field to achieve excellent actuation performance. In this work, we prepared DEs with very simple prescriptions by UV curing method. The prepared DEs have very low mechanical losses (<4%) and high dielectric constants (≥5.67) and obtain a large actuation strain (30.2%) under a relatively low electric field (31.6 kV/mm) with non-prestretching. This is because the soft butyl acrylate (BA) can guarantee the DEs with low Young's modulus and increase the dielectric constant by its polar functional group (-COO-), besides controlling the content of the cross-linker urethane acrylate (TR-U201XS) to regulate the cross-link density of the DEs and further influence its electromechanical properties, which are positive for improving the DEs' actuation performance. And the DEs can be used to fabricate a fishtail-type device, which obtains a large swing range of about 90°in air and can overcome the resistance of water to work in water.